The principle aim of this paper is to explore the existence. of periodic solutions with strictly positive components of generalized ecological competition systems governed by impulsive differential equation with infinite delays. Easily verifiable sufficient criteria are established. The approach is based on the coincidence degree theory and its related continuation theorem as well as some a priori estimates. Applications to some famous competition models, which have been widely studied in the literature, are presented also. (C) 2004 Elsevier Ltd. All rights reserved.