In vitro degradation behaviors of three-dimensional tissue engineering porous scaffolds made from amorphous poly(D,L-lactide-co-glycolide) with three different formulations have been systematically investigated up to 26 weeks in phosphate buffer saline solution at 37 degrees C. The following properties of the scaffolds were measured as a function of degradation time: dimensions, weight, compressive strength and modulus, polymer molecular weight and its distribution, and pore morphology. Of special interest was the determination of mechanical properties in wet environment. The pH of the PBS media was also detected. According to the characteristic changes of the various properties of porous scaffolds, the degradation process is suggested to be roughly divided into three stages tentatively named as quasi-stable stage, decrease-of-strength stage, loss-of-weight and disruption-of-scaffold stage.