Polylactic acid (PLA) is a biodegradable aliphatic polyester that is suitable for use in many fields related to medical treatment. This article reviews the glass transition temperature (T-g), the biodegradable rate of PLA blended with collagen (Col), and its mechanical properties through tensile, bending and impact testing, thermal analysis (DSC), scanning electron microscopy (SEM), and enzymatic hydrolysis. The results of the mechanical and SEM examination demonstrated partial biocompatibility. The T-g and crystallinity (x(c)) of the blends decreased with increasing collagen content. The tensile strength and bending strength changed from 53.826Mpa and 102.261Mpa to 11.707Mpa and 24.994Mpa, respectively. It was also found that the enzymatic hydrolysis rate of PLA increased with increasing collagen content. The weight of the blends decreased to half of the original weight after more than five weeks. Viscosity([eta]) and molecular weight (M-v) changed slowly in the period of enzymatic hydrolysis. It was concluded that the introduction of the collagen phase clearly diminished the mechanical properties of PLA, but the biodegradable property was improved. (C) 2004 Wiley Periodicals, Inc.