CERTIFICATION PURSUANT TO 18 U.S.C. SECTION
1350, AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002
In connection with the Annual Report of XBiotech
Inc. on Form 10-K for the period ended December 31, 2015 as filed with the Securities and Exchange Commission on the date hereof
(the “Report”), I, John Simard, Chief Executive Officer and President of the Company, certify, pursuant to 18 U.S.C.
§1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that to the best of my knowledge:
(1) The Report fully complies with the requirements
of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and
(2) The information contained in the Report fairly
presents, in all material respects, the financial condition and results of operations of XBiotech Inc.
||/s/ JOHN SIMARD
||Chief Executive Officer and President
||(Principal Executive Officer)
||Date: March 30, 2016