The six-membered lactide was polymerized using the ring-opening polymerization with lipase as a catalyst at a temperature between 80 and 130 degrees C in bulk to yield the corresponding polylactide with weight-average molecular weights of up to 126 000. The most preferable conditions with respect to the molecular weight of the polylactide are the bulk polymerization using lipase PS at a temperature of 100 degrees C. The D,L-lactide gave higher molecular weight compared to the D,D-and L,L-lactide.