Biodegradable foams derived from poly(lactic acid) (PLA) and starch were prepared by extrution using water as a blowing agent and talc as nucleation agent. Foam cellular size and size distribution was significantly affected by extrusion conditions (i.e., extruder temperature profiles, die diameters, and screw speed), and material compositions, (i.e., water concentration, PLA/starch ratio, and nucleation agent concentration). Foam with a relatively fine cellular size and uniform cellular size distribution was obtained under optimized conditions of PLA/starch ratio at 40/60, 15% water, 195 degrees C temperature before the die, 3-mm die nozzle diameter, 200-rpm screw speed, and 2% talc. (c) 2007 Wiley Periodicals, Inc.