This paper is concerned with the existence of periodic solutions for the fully second-order ordinary differential equation ( ) = ( , ( ), ( )), ∈ R, where the nonlinearity : R 3 → R is continuous and ( , , ) is 2 -periodic in . Under certain inequality conditions that ( , , ) may be superlinear growth on ( , ), an existence result of odd 2 -periodic solutions is obtained via Leray-Schauder fixed point theorem.