The effect of the compatibilizers, P(LLA-co-epsilonCL) and P(LLA-b-epsilonCL), on the morphology and hydrolysis of the blend of poly(epsilon-caprolactone) (PCL) and poly(L-lactide) (PLLA) was investigated. An addition of P(LLA-co-epsilonCL) or P(LLA-b-epsilonCL) into the blend could enhance the compatibility between the dispersed PCL domains and the PLLA matrix. The size of the PCL domains in the PLLA/ PCL (70/30) blend containing P(LLA-Co-epsilonCL) reduced more significantly with an increase in the content of the compatibilizer than that in the blend containing P(LLA-b-epsilonCL). The molecular weight of the PLLA/PCL blend films compatibilized with P(LLA-co-epsilonCL) or P(LLA-b-epsilonCL) decreased during the hydrolysis and the decrease of the molecular weight of the blend films compatibilized. with P(LLA-co-epsilonCL) was much more significant than that of the blend films compatibilized with P(LLA-b-epsilonCL).