Electronic Journal of Differential Equations, Vol. 2013 (2013), No. 29, pp. 1-5. Title: Existence of positive solutions for a nonlinear fractional differential equation Author: Habib Maagli (King Abdulaziz Univ., Rabigh, Saudi Arabia) Abstract: Using the Schauder fixed point theorem, we prove an existence of positive solutions for the fractional differential problem in the half line $\mathbb{R}^+=(0,\infty)$: $$ D^{\alpha}u=f(x,u),\quad \lim_{x \to 0^+}u(x)=0, $$ where $\alpha \in (1,2]$ and $f$ is a Borel measurable function in $\mathbb{R}^+\times \mathbb{R}^+$ satisfying some appropriate conditions. Submitted November 25, 2012. Published January 28, 2013. Math Subject Classifications: 34A08. Key Words: Riemann-Liouville fractional derivative; fixed point theorem.