The Ge-Sn-Te ternary system has been studied by thermal analysis (DTA and DSC), radiocrystallography on powders and metallography. No ternary compound has been found; the vertical section Ge-SnTe is a true pseudobinary section, while GeTe-SnTe presents a continuous solid solution.The study of six vertical sections allows us to identify two ternary reactions in the solid state (one of eutectoid type and one of transitory peritectoid type) and two ternary eutectic-type reactions.