Abstract The dysprosium-nickel phase diagram has been completed by X-rays in conjunction with differential thermal analysis. The intermetallic compound DyNi4 was detected, and the new intermetallic compound Dy4Ni17 was observed.In this system there exist ten intermetallic compounds: Dy3Ni,Dy3Ni2,DyNi,DyNi2,DyNi3,Dy2Ni7,DyNi4,Dy4Ni17,DyNi5, and Dy2Ni17. The intermetallic compounds DyNi and DyNi5 melt congruently at 1248℃and 1387℃, and the intermetallic compounds Dy3NiDy3Ni2,DyNi2,DyNi3,Dy2Ni7,DyNi4,Dy4Ni17 and Dy2Ni17 are formed by eight peritectic reactions at 762℃, 928℃, 1258℃, 1283℃, 1307℃, 1336℃, 1352℃ and 1321℃, respectively. Three eutectic reactions occur: at 31 at% Ni and 693℃, 56 at% Ni and 1173℃, 93 at% Ni and 1279℃. Neither Dy in Ni nor Ni in Dy shows any detectable solid solubility.