Porous poly(epsilon -caprolactone) (PCL) films were prepared by water extraction of poly(ethylene oxide) (PEO) from their solution-cast phase-separated blend films and the dependence of their blend ratio [X-PCL = PCL/(PEO + PCL)] and molecular weight of PEO on the porosity, pore size, crystallinity, crystalline thickness, mechanical properties, morphology, and enzymatic and alkaline hydrolysis of the porous PCL films were investigated. The film porosity or extracted weight ratio was in good agreement with the expected values, irrespective of X-PCL and molecular weight of PEO. The maximum pore size was larger for the porous films prepared using PEO having a lower molecular weight, compared with films prepared using PEO having a higher molecular weight at the same X-PCL. Differential scanning calorimetry of the porous PCL films revealed that their crystallinity and crystalline thickness were almost constant, regardless of X-PCL and molecular weight of PEO. The Young's modulus and tensile strength of the porous films decreased, whereas the elongation-at-break increased with decreasing X-PCL. The enzymatic and alkaline hydrolysis rates of the porous films increased with a decrease in X-PCL and an increase in the molecular weight of PEO. The porous PCL films having Young's modulus in the range of 2-24 kg/mm(2) and enzymatic hydrolysis rate in the range of one- to 20-fold that of the nonporous PCL film could be prepared by altering X-PCL and the molecular weight of PEO.