Since highly crystalline poly (L-lactide) (PLLA) degrades rather slowly in a biological environment and the crystalline domains remaining after partial degradation of the implant material give rise to an inflammatory response of the surrounding tissue, L-and D, L-lactide copolymer [P(L-DL)LA] having a low crystallinity is preferred in surgical applications. The thermal transitions and the mechanical properties of P (L-DL) LA rods were discussed in this paper. It was found that the self-reinforced P (L-DL) LA [SR-P(L-DL)LA] was strong enough in terms of mechanical properties compared with the self-reinforced PLLA [SR-PLLA].