Electronic Journal of Differential Equations, Vol. 2010(2010), No. 135, pp. 1-10. Title: A boundary value problem of fractional order at resonance Author: Nickolai Kosmatov (Univ. of Arkansas, Little Rock, AR, USA) Abstract: We establish solvability of a boundary value problem for a nonlinear differential equation of fractional order by means of the coincidence degree theory. Submitted June 8, 2010. Published September 20, 2010. Math Subject Classifications: 34A34, 34B10, 34B15. Key Words: Caratheodory conditions; resonance; Riemann-Liouville derivative; Riemann-Liouville integral.