Electronic Journal of Differential Equations, Vol. 2012 (2012), No. 153, pp. 1-12. Title: Existence of mild solutions for a neutral fractional equation with fractional nonlocal conditions Author: Nasser-eddine Tatar (King Fahd Univ. Dhahran, Saudi Arabia) Abstract: The existence of mild solutions in an appropriate space is established for a second-order abstract problem of neutral type with derivatives of non-integer order in the nonlinearity as well as in the initial conditions. We introduce some new spaces taking into account the minimum requirements of regularity. Submitted May 5, 2012. Published September 07, 2012. Math Subject Classifications: 26A33, 34K40, 35L90, 35L70, 35L15, 35L07. Key Words: Cauchy problem; cosine family; fractional derivative; mild solutions; neutral second-order abstract problem.