The solubility of nitrogen, oxygen, carbon dioxide and water in poly(lactic acid) (PLA) was measured using a quartz crystal microbalance (QCM). For that purpose an apparatus based on the quartz crystal microbalance technique was built. This apparatus was calibrated with the system carbon dioxide in atactic polystyrene and the determined precision was of 3%. Measurements were performed up to atmospheric pressure and in the temperature region from 293.2 to 313.2 K. A study of the solubility of carbon dioxide in PLA over a temperature range from 283.2 to 313.2 K and at pressures bellow the atmospheric will be presented. The experimental results obtained were correlated with the Flory-Huggins model with an overall AAD of 6%. (C) 2004 Elsevier B.V. All rights reserved.