The samarium-nickel binary system has been studied by X-ray diffraction, differential thermal and metallographic analyses. The phase diagram has been determined. In the system the following eight intermetallie compounds were observed: Sm3Ni(decomposes at 664℃), SmNi (M. P. 1079℃), SmNi2 (decomposes at 1034℃), SmNi,(decomposes at 1135℃), Sm2Ni7 (decomposes at 122℃), SmNi4 (decomposes at1282℃), SmNi5 (M. P. 143℃), and Sm2Ni17 (decomposes at 1288℃). Three eutec-tics occur: Sm,Ni-SmNi (570℃,～32 at%Ni), SmNi-SmNi2 (809℃, 53.5 at%Ni) andSm2Ni17-Ni (128℃, 94 at%Ni). Neither Sm in Ni nor Ni in Sm shows any detectablesolid solubility.