Abstract
In this paper, we study the existence of periodic solutions of the nonlinear neutral system of differential equations
d/dtx(t) = A(t)x(t- tau (t)) + d/st Q (t, x (t - g(t))) + G (t, x(t) , x (t - g (t))).
By using Krasnoselskii's fixed point theorem we obtain the existence of periodic solution and by contraction mapping principle we obtain the uniqueness. Our results extend and complement some earlier publications.