The goal of this paper is to establish the existence of infinitely many homoclinic orbits for a class of second order Hamiltonian systems of the form:Here q E R n , and we assume the n x n matrix L(t) satisfies (L) is T-periodic in t, and is symmetric and positive definite uniformly for Integrating (V 3 ) shows V(t, q) = o( lqI2) as Iql ~ 0 and V(t, q)lql-2 ~ 00 as Iql ~ 00 , i.e., V is a "superquadratic" potential.Our approach to (HS) involves the use of variational methods of a mini-max nature. To describe them more fully, let E = Wi ,2(R, Rn) under the usual normThus E is a Hilbert space and it is not difficult to show that E C CO (R, Rn) , the space of continuous functions q on R such that q(t) ~ 0 as It I ~ 00 (see,