The neodymium-nickel binary system has been studied by X-ray diffraction method and differential thermal analysis and the phase diagram determined.In this system, the following eight intermetallic compounds were observed: Nd3 Ni (M. P. 590℃), Nd7Ni3(M. P. 616℃), NdNi (M.P.780℃), NdNi2(decomposes at 940℃),NdNi3 (decomposes at 1030℃), Nd2Ni7 (decomposes at 1234℃), NdNi5(M.P. 1420℃)and Nd2Ni17. Intermetallic compound Nd2Ni17 forms peritectically 1300℃ and decomposes through a eutectoid reaction into Ni and NdNi5 at 1250℃. Five eutectics occur: Nd-Nd3Ni (570℃,～19at%Ni), Nd3Ni-Nd7Ni3 (565℃,～27at%Ni),Nd7Ni3-NdNi (540℃,～35at%Ni),NdNi-NdNi2(720℃,56at%Ni) and Nd2Ni17-Ni (1290℃,91at%Ni). Neither Nd in Ni nor Ni in Nd shows any detectable solid solubility.