Electronic Journal of Differential Equations, Vol. 2013 (2013), No. 07, pp. 1-7. Title: Nonlocal fractional semilinear differential equations in separable Banach spaces Authors: Kexue Li (Xi'an Jiaotong Univ., China) Jigen Peng (Xi'an Jiaotong Univ., China) Jinghuai Gao (Xi'an Jiaotong Univ., China) Abstract: In this article, we study the existence of mild solutions for fractional semilinear differential equations with nonlocal conditions in separable Banach spaces. The result is obtained by using the Hausdorff measure of noncompactness and the Schauder fixed point theorem. Submitted June 26, 2012. Published January 08, 2013. Math Subject Classifications: 26A33. Key Words: Fractional differential equation; nonlocal conditions; Hausdorff measure of noncompactness; mild solution.