A pseudo-binary phase diagram between the perovskite Pb(Mg1/3Nb2/3)O3 and PbO was established by DTA. The m.p. of PMN was found at 1320 Deg and the eutectic temp. at 830+-2 Deg with the eutectic compn. of 74%PbO/26%PMN (in wt%). On the basis of the detd. phase diagram, single crystals of the perovskite phase were grown by the high temp. soln. technique by using 30 wt.% PbO as solvent. The crystals show pseudo-cubic form with (100)cub growth steps or degenerated forms. Size (.apprx. 1cm) and quality of the obtained crystals are adequate for phys. characterizations.