Poly(epsilon-caprolactone) (PCL) and poly[(R)-3-hydroxybutyrate] (R-PHB) films with pores and hydrophilic surfaces were prepared by the water extraction of poly(ethylene oxide) from as-cast blend films (1:1) and by the alkali treatment of as-cast nonporous films, respectively. These films, as well as as-cast nonporous PCL and R-PHB films, were biodegraded in static seawater kept at 25degreesC, and their biodegradation was monitored with gravimetry, gel permeation chromatography (GPC), and scanning electron microscopy. The pores or highly hydrophilic surfaces of the PCL and R-PHB films enhanced their biodegradation in seawater. Moreover, GPC measurements could be used to trace the biodegradation in seawater when the biodegradation proceeded to a great extent. (C) 2003 Wiley Periodicals, Inc.