The effects of entry in Bertrand and Cournot oligopolies with product differentiation and single product firms are analyzed, assuming that firms producing differentiated goods are uniformly increased similarly as consumers in a replicated economy. It is found that under general conditions, the limit points of the equilibrium Bertrand prices do not coincide with the perfect competitive equilibrium. We prove that the limit points always exceed the marginal costs. Two cases are considered for Cournot oligopoly, in one of which firms producing the same goods collude, and in the other collusion is ruled out. Under some simplifying assumptions, the limit points of the equilibrium Cournot prices always exceed the competitive prices in the former case, but in the latter one the equilibrium Cournot prices converge to the competitive prices.