in this paper, the Sturm-Liouville-like four-point boundary value problem with a p-Laplacian operator (Phi(p)(u '))'(t) + lambda.a(t)f(t,u(t)) =0, t is an element of (0,1), u(0) - xu '(xi) =0, u(1) + chi u '(eta) = 0 is studied, where Phi(p)(s) = vertical bar s vertical bar(p-2)s, p > 1. By the use of fixed point index theory, Leray-Schauder degree and upper and lower solution method, some existence, nonexistence and multiplicity results of symmetric positive solutions are acquired. (c) 2006 Published by Elsevier Inc.