The porous poly (epsilon-caprolactone) (PCL) membranes were prepared by solvent-casting-leaching method, and PEG(10.000) as well as PEG(4000) were used as the pore formers. The properties of membranes were characterized by SEM, DSC, FTIR, H-1 NMR, and their thickness as well as porosity. The thickness of membranes were well controlled in the range of 71.0 +/- 13.0 similar to 85.0 +/- 1.7 mum. From SEM micrographs, the pores formed were spherical and had identical size, and the size of micropores created by PEG(4000) was larger than that by PEG(10.000). The calculated porosity in membranes increased proportion to the amount of Poly(ethylene glycol) (PEG) blended initially which was irrespective of the molecular weight (M-W) of PEG. The FTIR and DSC data showed that there is no significant interaction between PCL and PEG. In permeation study, theophylline and FITC-dextran were used as the model compounds. Once the porosity increased above the critical value 0.35, reducing the dead-end fraction, resulting in increasing permeability. The permeability of drug from porous membranes formed by PEG(4000) was faster than that by PEG(10.000). In addition, the permeation rate of theophylline was higher than that of FITC-dextran. This was attributed to smaller hydrodynamic radius of theophylline (0.3 nm) than FITC-dextran (4.7 nm) and the partition of theophylline to the PCL membrane (K = 0.095).