Structure and properties of a bioabsorbable poly(glycolide-co-lactide) (PGA-co-PLA) fiber during several processing stages and the final in vitro degradation stage were investigated by means of wide-angle X-ray diffraction, dynamic mechanical analysis and mechanical property tests. In the orientation stage, an increase in the temperature of the first encountered orientation roll resulted in a lower level of crystallinity and larger crystallites. The temperature of the second encountered pre-annealing roll (PR) imposed a smaller effect on the structure. In the hot-stretching stage after fibers were braided, the maximum crystallinity was achieved at around 126 degreesC. Higher hot-stretching temperatures increased the crystal size, glass transition temperature (T-g) and tensile strength, but decreased the elongation at break and the heat shrinkage near T-g. In the post-annealing stage, it was found that crystallinity, T-g and tensile strength all increased significantly while the beat shrinkage near T-g sharply decreased after annealing. This suggests that the internal stress accumulated in the orientation and hot-stretching stages can he effectively reduced by post-annealing. During in vitro degradation, crystallinity was found to increase with time while the heat shrinkage near T-g and in the supercooling region (T-g < T < T-m) was greatly reduced. These results support the process of cleavage-induced crystallization.