This article describes the compatibility of two semicrystalline polymers, poly(epsilon-caprolactone) (PCL) and poly(l-lactic acid) (PLLA). The compatibility of the PCL/PLLA blends was enhanced by the compatibilizing effect of the poly(l,l-lactide-co-epsilon-caprolactone) [P(lLA-co-epsilon CL)]. A discussion details the effect of the concentration of the compatibilizing agent, the copolymer of I,l-lactide and epsilon-caprolactone of a 50/50 mol ratio [P(lLA-co-epsilon CL)], on the compatibility and the crystallization behavior of the blends of PCL and PLLA. It was found that the addition of P(lLA-co-epsilon CL) could suppress the crystallization of PLLA at its T-c and induced the concurrent crystallization of PLLA and PCL.