A grease composition for a constant-velocity joint includes: (a) a base oil having a kinematic viscosity of 16.0 mm.sup.2/s or more at 100 C. and a viscosity index of 90 or more; (b) a diurea-based thickener, for example, an aliphatic diurea; (c) 0.2 to 2.0% by mass of zinc dialkyldithiophosphate; (d) 0.5 to 2.0% by mass of non-oil-soluble molybdenum dialkyl dithiocarbamate; (e) 0.5 to 3.0% by mass of oil-soluble molybdenum dialkyl dithiocarbamate; (f) 1.0 to 4.0% by mass of zinc dialkyldithiocarbamate; and (g) 0.1 to 1.5% by mass of a benzothiazole-thione or a derivative thereof, wherein (f):(g)=8:1 to 3:1 (mass ratio).