Transparent 0.9Pb(Mg1/3Nb2/3)O-3-0.1PbTiO(3) (PMN-PT) based ceramics were prepared by a conventional solid-state synthesis without using a hot-press method. The ceramics became transparent when they were sintered in an O-2 atmosphere. The optical transmission increased with decreasing diameter of the calcined powder, which was controlled by the size of zirconia ball-milling media. Substitution of 3mol% La for Pb in PMN-PT further increased the optical transmission to 68% at the wavelength of 2000nm, which was comparable to that of hot-pressed Pb(Mg1/3Nb2/3)O-3-PbTiO3 based transparent ceramics.