We use Krasnoselskii's fixed point theorem to prove the existence of positive periodic solutions of the second-order nonlinear neutral differential equation d(2)/dt(2) x(t) + p(t) d/dt x(t) + q(t)x(t) = c d/dt x(t - tau(t))+ f(t, h(x(t)), g(x(t- tau(t)))).