Electronic Journal of Differential Equations, Vol. 2006(2006), No. 36, pp. 1-12. Title: Positive solutions for boundary-value problems of nonlinear fractional differential equations Author: Shuqin Zhang (Univ. of Mining and Tech., Beijing, China) Abstract: In this paper, we consider the existence and multiplicity of positive solutions for the nonlinear fractional differential equation boundary-value problem $$\displaylines{ \mathbf{D}_{0+}^\alpha u(t)=f(t,u(t)),\quad 0