The sintering and piezoelectric properties of Pb(Ni1/3Sb2/3)O-3-PbZrO3-PbTiO3 ceramics have been investigated. When the powders contain 48 mol% PbTiO3 and less than 10 mol% Pb(Ni1/3Sb2/3)O-3 followed by calcination at 850degreesC for 2 h, the calcine only contains the perovskite structure; but if the Pb(Ni1/3Sb2/3)O-3 content is between 12 mol% and 14 mol%, both tetragonal and rhombohedral phases are obtained. The composition of the morphotropic phase boundary(MPB) in the Pb(Ni1/3Sb2/3)O-3-PbZrO3-PbTiO3 system is Pb(Ni1/3Sb2/3)O-3 = 12 mol%, PbZrO3 = 40 mol% and PbTiO3 = 48 mol%. As the composition at the MPB is sintered at 1260degreesC and 1280degreesC for 2 h, respectively, the maximum density (7.8 g/cm(3)) is obtained. The SEM micrographs indicate that a decrease in porosity with increasing sintering temperature is attained at 1280degreesC, which is due to a decrease in the number and size of pores. When the sintering temperature is higher than 1280degreesC, the porosity increases due to PbO evaporation leading to an increase of the number of pore sites and in enlargement of the pore diameter. When the compact composition at MPB is sintered at 1280degreesC for 2 h, the planar coupling coefficient (K-p) and mechanical quality coefficient (Q(m)) tend to approach the maximum (0.488) and minimum values (292.5), respectively.