In this paper, a two-strain epidemic model with saturating contact rates is considered. It is shown that if the social activity of infected individuals does not vary with strains, then the competitive exclusion principle holds; if the social activity of infected individuals varies with different strains, the coexistence of pathogens is possible under a certain condition which involves the invasion reproduction numbers. The stability of the dominance equilibria and coexistence equilibrium is also examined. Numerical simulations are presented to illustrate the results. © 2008 Elsevier Ltd. All rights reserved.