The stereoselective polymerization of partial rac-lactide was attempted by using crystallization during polymerization. Polymerizations were carried out with trifluoromethanesulfonic acid in a mixed solvent of toluene and octane. The molar content Of L-lactate in the feed was 95%. Polymerization proceeded with the elimination of D-lactate by means of crystallization. Poly(L-lactic acid) (PLLA) crystals were first precipitated and then plate-like poly(lactic acid) (PLA) crystals were finally obtained, of which the composition Of L-lactate was 97.6% and the (M) over bar (n) was 1.68 x 10(4).