Exhibit 4.1

          TENTH SUPPLEMENTAL INDENTURE (this “Supplemental Indenture”), dated as of June 16, 2011, among ALERE INC., a Delaware corporation (the “Issuer”), each of the Guarantors under the Indenture referred to below (the “Guarantors”), and U.S. BANK NATIONAL ASSOCIATION, as Trustee under the Indenture referred to below (the “Trustee”).

WITNESSETH:

          WHEREAS the Issuer has heretofore executed and delivered to the Trustee an Indenture dated as of May 12, 2009, as amended, supplemented and modified by a First Supplemental Indenture dated as of May 12, 2009, a Second Supplemental Indenture dated as of June 9, 2009, a Third Supplemental Indenture dated as of August 4, 2009, a Fourth Supplemental Indenture dated as of September 22, 2009, a Fifth Supplemental Indenture dated as of November 25, 2009, a Sixth Supplemental Indenture dated as of February 1, 2010, a Seventh Supplemental Indenture dated as of March 1, 2010 and an Eighth Supplemental Indenture dated as of March 19, 2010 (as so amended, supplemented and modified, and as further amended, supplemented or modified to date, the “Indenture”), by and among the Issuer, the Guarantors and the Trustee, providing for the issuance of 9.00% Senior Subordinated Notes due 2016 (the “Notes”);

          WHEREAS, pursuant to that certain Consent Solicitation Statement dated May 31, 2011, as amended and supplemented to date (the “Consent Solicitation Statement”), the Issuer solicited the consents of the holders of the Notes to the Record Date Amendments and Waivers (as defined in the Consent Solicitation Statement) with respect to the Indenture;

          WHEREAS, the approval by written consent of the holders of at least a majority of the aggregate principal amount of the Notes outstanding as of April 29, 2011 (the “Record Date”), which is the record date fixed by the Issuer in accordance with Section 9.05 of the Indenture, of which record date the Trustee has been duly notified in writing by the Issuer in accordance with Section 9.05, is sufficient to approve the aforesaid Record Date Amendments and Waivers in accordance with the Indenture;

          WHEREAS, having received the approval of the holders of at least a majority of the aggregate principal amount of the Notes outstanding as of the Record Date (the “Requisite Consent”) pursuant to Section 9.02(a) of the Indenture with respect to the Record Date Amendments and Waivers, the Issuer, the Guarantors and the Trustee desire to effect the Record Date Amendments and Waivers as provided hereinafter;

          WHEREAS, all conditions precedent set forth in the Consent Solicitation Statement and the Indenture to the execution and delivery of this of this Supplemental Indenture by the Issuer, the Guarantors and the Trustee have been satisfied, and all things necessary have been done to make this Tenth Supplemental Indenture, when executed and delivered by the Issuers and the Guarantors, the legal, valid and binding agreement of the Issuers and the Guarantors, in accordance with its terms; and

          WHEREAS, the Issuer and the Guarantors have requested that the Trustee execute and deliver this Tenth Supplemental Indenture;

          NOW, THEREFORE in consideration of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged, the parties to this Tenth Supplemental Indenture hereby agree as follows:

          SECTION 1. Definitions. For all purposes of this Supplemental Indenture, except as otherwise herein expressly provided or unless the context otherwise requires: (i) the terms and expressions used herein shall have the same meanings as corresponding terms and expressions used in the Indenture; and (ii) the words “herein,” “hereof” and “hereby” and other words of similar import used in this Supplemental Indenture refer to this Supplemental Indenture as a whole and not to any particular section hereof.

          SECTION 2. Amendment of Section 9.05. The first sentence of the second paragraph of Section 9.05 of the Indenture (Revocation and Effect of Consents) is hereby amended and restated in its entirety as follows:

     “The Issuer may, but shall not be obligated to, fix a record date for the purpose of determining the Holders entitled to consent to any amendment, supplement or waiver, which record date shall be any date the Issuer shall select for such purpose in its sole discretion.”

          SECTION 3. Record Date Waivers. In accordance with Section 9.02(a) of the Indenture, the Record Date Waivers (as defined in the Consent Solicitation Statement), having received the Requisite Consent, are hereby effective (subject to Section 4) in accordance with Article IX of the Indenture and incorporated herein by reference.

          SECTION 4. Effectiveness of Amendments and Waivers. This Supplemental Indenture shall be effective upon execution hereof by the Issuer, the Guarantors and the Trustee; provided, however, that the aforesaid Record Date Amendments and Waivers shall not take effect until the payment of the Consent Fee (as defined in the Consent Solicitation Statement) in accordance with the Consent Solicitation Statement. If the Consent Solicitation (as defined in the Consent Solicitation Statement) is terminated, withdrawn or otherwise not completed in accordance with the Consent Solicitation, or the Consent Fee is not paid in accordance with the Consent Solicitation Statement, this Supplemental Indenture shall automatically become null and void ab initio.

          SECTION 5. Ratification of Indenture; Supplemental Indenture Part of Indenture. Except as expressly modified hereby, the Indenture is in all respects ratified and confirmed and all the terms, conditions and provisions thereof shall remain in full force and effect. This Supplemental Indenture shall form a part of the Indenture for all purposes, and every Holder of Notes heretofore or hereafter authenticated and delivered shall be bound hereby.

          SECTION 6. Governing Law. This Supplemental Indenture shall be governed by, and construed in accordance with, the laws of the State of New York, but without giving effect to applicable principles of conflicts of laws to the extent that the application of the laws of another jurisdiction would be required thereby.

          SECTION 7. Trustee Makes No Representation. The Trustee makes no representation as to the validity or sufficiency of this Supplemental Indenture.

          SECTION 8. Counterparts. The parties may sign any number of copies of this Supplemental Indenture. Each signed copy shall be an original, but all of them together represent the same agreement.

          SECTION 9. Effect of Headings. The Section headings herein are for convenience only and shall not effect the construction thereof.

[Signature Page Follows]

          IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be duly executed as of the date first above written.

Signature Page to Tenth Supplemental Indenture — 9.0% Notes due 2016

Signature Page to Tenth Supplemental Indenture — 9.0% Notes due 2016

Signature Page to Tenth Supplemental Indenture — 9.0% Notes due 2016

Signature Page to Tenth Supplemental Indenture — 9.0% Notes due 2016

Signature Page to Tenth Supplemental Indenture — 9.0% Notes due 2016