The sintering behaviour of monodispersed ZnS powders having particle size of 0.1-0.9 mu m, which were prepared from aqueous zinc nitrate solution by a homogeneous precipitation method using thioacetamide, was studied. Dry-pressed pellets of ZnS powders were fired at 900-1250 degrees C for 2 h in a nitrogen atmosphere. Monodispersed ZnS powders showed high sinterability in comparison with agglomerated or aggregated ZnS powders. The sinterability increased with decrease in particle size, and ZnS powders with particle size of 0.1 mu m were densified to above 98% theoretical density by conventional sintering at 1000 degrees C for 2 h. Ultrafine monodispersed, spherical particles gave a uniform and fine-grained microstructure.