By the methods of differential thermal, X-ray phase, microstructural analyses and micro­hardness and alloy density testing, phase equilibria in a ternary system La₂S₃–Ga₂S₃–EuS have been investigated. The phase diagrams of some polymeric cuts and projections of liquidus surface were plotted. The regions of primary crystal­li­zation of all phases as well as coordinates of all non- and mono-variant equilibria were established in the studied.