The results of the investigation of phase equilibria in the Ag8SnSe6-Ag7SnSe5I system by differential thermal analysis and X-ray phase analysis are presented. It was established that the Ag8SnSe6-Ag7SnSe5I system is characterized by the formation of a continuous series of solid solutions between Ag7SnSe5I and the hightemperature cubic modification of Ag8SnSe6, as well as limited solid solutions based on the low-temperature modification of the latter compound. The formation of solid solutions leads to a decrease in the polymorphic transition temperature of Ag₈SnSe₆ and stabilization of the high-temperature cubic phase at room temperature. The obtained results are of interest from the viewpoint of crystal growth of solid solutions with Se↔I substitution in the Ag8SnSe6-Ag7SnSe5I system.