Poly(D,L-lactide-co-glycolide) samples with different glycolide contents, ie 85:15, 75:25 and 50:50 mole ratios of lactide to glycolide, and poly(L-lactide) were obtained from a commercial source. Polymer films of 15 pm thickness were prepared by a solvent-casting method. Degradation studies were conducted at 37 degrees C in pH 7.4 phosphate buffered saline and in bovine serum albumin solution. The degradation behaviour of the films was followed by UV and FTIR spectrophotometry and viscometric and gravimetric measurements. Spectroscopic investigations showed that during the first month of degradation, both the chain length and the chain chemical structure changed, especially in the presence of bovine serum albumin. The short chains are attributed to the formation of new eater groups; however, the end-groups may be aldehyde- or ketone-like structures. While the intrinsic viscosities of all polymers decreased continuously after being exposed to the degradation media, insignificant mass loss occurred during the experimental investigation. (C) 2000 Society of Chemical Industry.