Exhibit 10.1

FOURTH AMENDMENT TO CREDIT AGREEMENT

          THIS AMENDMENT TO CREDIT AGREEMENT (this "Amendment") is entered into as of October 29, 2009, by and between MEDTOX SCIENTIFIC, INC., MEDTOX DIAGNOSTICS, INC. and MEDTOX LABORATORIES, INC., each a Delaware corporation (each individually a "Borrower"), and WELLS FARGO BANK, NATIONAL ASSOCIATION ("Bank"). Each reference herein to “Borrower” shall mean each and every party, collectively and individually, defined above as a Borrower.

RECITALS

          WHEREAS, Borrower is currently indebted to Bank pursuant to the terms and conditions of that certain Credit Agreement between Borrower and Bank dated as of December 1, 2005, as amended from time to time ("Credit Agreement").

          WHEREAS, Bank and Borrower have agreed to certain changes in the terms and conditions set forth in the Credit Agreement and have agreed to amend the Credit Agreement to reflect said changes.

          NOW, THEREFORE, for valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree that the Credit Agreement shall be amended as follows:

          1.         Section 1.1 (a) is hereby amended by deleting "November 1, 2009" as the last day on which Bank will make advances under the Line of Credit, and by substituting for said date "August 31, 2011," with such change to be effective upon the execution and delivery to Bank of a promissory note dated as of October 29, 2009, (which promissory note shall replace and be deemed the Line of Credit Note defined in and made pursuant to the Credit Agreement) and all other contracts, instruments and documents required by Bank to evidence such change.

          2.         Section 1.4 (e) is hereby deleted in its entirety, and the following substituted therefor:

                      “(e) Unused Commitment Fee. Borrower shall pay to Bank a fee equal to one quarter of one percent (0.25%) per annum (computed on the basis of a 360-day year, actual days elapsed) on the average daily unused amount of the Line of Credit, which fee shall be calculated on a quarterly basis by Bank and shall be due and payable by Borrower in arrears within ten (1) days after each billing is sent by Bank.”

          3.         Section 4.9 (a) is hereby deleted in its entirety, and the following substituted therefor:

                      “(a) Tangible Net Worth not less than $40,000,000.00 at any time, with “Tangible Net Worth” defined as the aggregate of total stockholders’ equity plus subordinated debtless any intangible assets.”

“(d) Current Ratio not less than 1.3 to 1.0 at each month end, with “Current Ratio” defined as total current assets divided by total current liabilities.”            

          5.         Except as specifically provided herein, all terms and conditions of the Credit Agreement remain in full force and effect, without waiver or modification. All terms defined in the Credit Agreement shall have the same meaning when used in this Amendment. This Amendment and the Credit Agreement shall be read together, as one document.

          6.         Borrower hereby remakes all representations and warranties contained in the Credit Agreement and reaffirms all covenants set forth therein. Borrower further certifies that as of the date of this Amendment there exists no Event of Default as defined in the Credit Agreement, nor any condition, act or event which with the giving of notice or the passage of time or both would constitute any such Event of Default.

          IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed as of the day and year first written above.

Title: V.P./CFO__________________

MEDTOX DIAGNOSTICS, INC.

By: /s/ Kevin J. Wiersma___________

Title: V.P./CFO__________________

MEDTOX LABORATORIES, INC.

By: /s/ Kevin J. Wiersma___________

Title: V.P./CFO__________________

REVOLVING LINE OF CREDIT NOTE

_____________________

          FOR VALUE RECEIVED, the undersigned MEDTOX SCIENTIFIC, INC., MEDTOX DIAGNOSTICS, INC., and MEDTOX LABORATORIES, INC. ("Borrower") promises to pay to the order of WELLS FARGO BANK, NATIONAL ASSOCIATION ("Bank") at its office at 6^th and Marquette, Minneapolis, Minnesota 55479, or at such other place as the holder hereof may designate, in lawful money of the United States of America and in immediately available funds, the principal sum of Eight Million Dollars ($8,000,000.00), or so much thereof as may be advanced and be outstanding, with interest thereon, to be computed on each advance from the date of its disbursement as set forth herein.

DEFINITIONS:

          As used herein, the following terms shall have the meanings set forth after each, and any other term defined in this Note shall have the meaning set forth at the place defined:

          (a)       "Business Day" means any day except a Saturday, Sunday or any other day on which commercial banks in Minnesota are authorized or required by law to close.

          (b)       "Daily Three Month LIBOR" means, for any day, the rate of interest equal to LIBOR then in effect for delivery for a three (3) month period.

          (c)       "LIBOR" means the rate per annum (rounded upward, if necessary, to the nearest whole 1/8 of 1%) and determined pursuant to the following formula:

                      (i)        "Base LIBOR" means the rate per annum for United States dollar deposits quoted by Bank as the Inter-Bank Market Offered Rate, with the understanding that such rate is quoted by Bank for the purpose of calculating effective rates of interest for loans making reference thereto, for delivery of funds for three (3) months in an amount equal to the outstanding principal balance of this Note. Borrower understands and agrees that Bank may base its quotation of the Inter-Bank Market Offered Rate upon such offers or other market indicators of the Inter-Bank Market as Bank in its discretion deems appropriate including, but not limited to, the rate offered for U.S. dollar deposits on the London Inter-Bank Market.

                      (ii)       "LIBOR Reserve Percentage" means the reserve percentage prescribed by the Board of Governors of the Federal Reserve System (or any successor) for "Eurocurrency Liabilities" (as defined in Regulation D of the Federal Reserve Board, as amended), adjusted by Bank for expected changes in such reserve percentage during the term of this Note.

INTEREST:

          (a)       Interest. The outstanding principal balance of this Note shall bear interest (computed on the basis of a 360-day year, actual days elapsed) at a fluctuating rate per annum determined by Bank to be two and one quarter of one percent (2.25%) above Daily Three Month

LIBOR in effect from time to time. Each change in the rate of interest hereunder shall become effective on each Business Day a change in Daily Three Month LIBOR is announced within Bank. Bank is hereby authorized to note the date and interest rate applicable to this Note and any payments made thereon on Bank's books and records (either manually or by electronic entry) and/or on any schedule attached to this Note, which notations shall be prima facie evidence of the accuracy of the information noted.

          (b)       Taxes and Regulatory Costs. Borrower shall pay to Bank immediately upon demand, in addition to any other amounts due or to become due hereunder, any and all (i) withholdings, interest equalization taxes, stamp taxes or other taxes (except income and franchise taxes) imposed by any domestic or foreign governmental authority and related in any manner to LIBOR, and (ii) future, supplemental, emergency or other changes in the LIBOR Reserve Percentage, assessment rates imposed by the Federal Deposit Insurance Corporation, or similar requirements or costs imposed by any domestic or foreign governmental authority or resulting from compliance by Bank with any request or directive (whether or not having the force of law) from any central bank or other governmental authority and related in any manner to LIBOR to the extent they are not included in the calculation of LIBOR. In determining which of the foregoing are attributable to any LIBOR option available to Borrower hereunder, any reasonable allocation made by Bank among its operations shall be conclusive and binding upon Borrower.

          (c)       Payment of Interest. Interest accrued on this Note shall be payable on the first day of each month, commencing November 1, 2009.

          (d)       Default Interest. From and after the maturity date of this Note, or such earlier date as all principal owing hereunder becomes due and payable by acceleration or otherwise, or at Bank's option upon the occurrence, and during the continuance of an Event of Default, the outstanding principal balance of this Note shall bear interest at an increased rate per annum (computed on the basis of a 360-day year, actual days elapsed) equal to four percent (4%) above the rate of interest from time to time applicable to this Note.

BORROWING AND REPAYMENT:

          (a)       Borrowing and Repayment. Borrower may from time to time during the term of this Note borrow, partially or wholly repay its outstanding borrowings, and reborrow, subject to all of the limitations, terms and conditions of this Note and of any document executed in connection with or governing this Note; provided however, that the total outstanding borrowings under this Note shall not at any time exceed the principal amount stated above. The unpaid principal balance of this obligation at any time shall be the total amounts advanced hereunder by the holder hereof less the amount of principal payments made hereon by or for Borrower, which balance may be endorsed hereon from time to time by the holder. The outstanding principal balance of this Note shall be due and payable in full on August 31, 2011.

          (b)       Advances. Advances hereunder, to the total amount of the principal sum stated above, may be made by the holder at the oral or written request of (i) Richard J. Braun or Kevin J. Wiersma, any one acting alone, who are authorized to request advances and direct the disposition of any advances until written notice of the revocation of such authority is received by the holder at the office designated above, or (ii) any person, with respect to advances deposited to the credit of any deposit account of Borrower, which advances, when so deposited, shall be conclusively presumed to have been made to or for the benefit of Borrower regardless of the fact that persons other than those authorized to request advances may have authority to draw

against such account. The holder shall have no obligation to determine whether any person requesting an advance is or has been authorized by Borrower.

          (c)       Application of Payments. Each payment made on this Note shall be credited first, to any interest then due and second, to the outstanding principal balance hereof.

EVENTS OF DEFAULT:

          This Note is made pursuant to and is subject to the terms and conditions of that certain Credit Agreement between Borrower and Bank dated as of December 1, 2005, as amended from time to time (the "Credit Agreement"). Any default in the payment or performance of any obligation under this Note, or any defined event of default under the Credit Agreement, shall constitute an "Event of Default" under this Note.

MISCELLANEOUS:

          (a)       Remedies. Upon the occurrence of any Event of Default, the holder of this Note, at the holder's option, may declare all sums of principal and interest outstanding hereunder to be immediately due and payable without presentment, demand, notice of nonperformance, notice of protest, protest or notice of dishonor, all of which are expressly waived by Borrower, and the obligation, if any, of the holder to extend any further credit hereunder shall immediately cease and terminate. Borrower shall pay to the holder immediately upon demand the full amount of all payments, advances, charges, costs and expenses, including reasonable attorneys' fees (to include outside counsel fees and all allocated costs of the holder's in-house counsel), expended or incurred by the holder in connection with the enforcement of the holder's rights and/or the collection of any amounts which become due to the holder under this Note, and the prosecution or defense of any action in any way related to this Note, including without limitation, any action for declaratory relief, whether incurred at the trial or appellate level, in an arbitration proceeding or otherwise, and including any of the foregoing incurred in connection with any bankruptcy proceeding (including without limitation, any adversary proceeding, contested matter or motion brought by Bank or any other person) relating to Borrower or any other person or entity.

          (b)       Obligations Joint and Several. Should more than one person or entity sign this Note as a Borrower, the obligations of each such Borrower shall be joint and several.

          (c)       Governing Law. This Note shall be governed by and construed in accordance with the laws of the State of Minnesota.

          IN WITNESS WHEREOF, the undersigned has executed this Note as of the date first written above.

MEDTOX SCIENTIFIC, INC.

By: /s/ Kevin J. Wiersma___________

Title: V.P./CFO__________________

MEDTOX DIAGNOSTICS, INC.

By: /s/ Kevin J. Wiersma___________

Title: V.P./CFO__________________

MEDTOX LABORATORIES, INC.

By: /s/ Kevin J. Wiersma___________

Title: V.P./CFO__________________