We consider the existence of positive solutions of the equation 1/lambda(t)(lambda(t)phi(p)(x'(t)))' + mu f(t, x(t), x'(t)) = 0, where phi(p)(s) = vertical bar s vertical bar(p-2)s,p > 1, subject to some singular Sturm-Liouville boundary conditions. Using the Krasnosel'skii fixed point theorem for operators on cones, we prove the existence of positive solutions under some structure conditions.