Abstract
The models of interregional trade under monopolistic competition of producers are studied. The situations of market equilibrium and social optimality are considered. it is shown: (1) in a situation of symmetrical market equilibrium, the elasticities of production costs are a convex combination of elasticities of revenue from individual consumption; (2) in a situation of symmetrical social optimality, the elasticities of production costs are a convex combination of elasticities of elementary utilities from individual consumption.