During the past five years, important advances have been accomplished in the understanding of the fate of aliphatic polyesters derived from lactic acid (LA) and glycolic acid (GA) in aquous media. Hydrolysis of solid LA/GA polymers is now regarded as depending on a diffusion-reaction mechanism. Faster central degradation and degradation-induced composition and morphology changes are three of the most important findings which appeared to be composition dependent as deduced from the behaviors of different LA/GA polymers. Attempt is made to generalize these findings to the whole family and to elaborate a map which could be used to predict degradation characteristics of LA/GA polymers from their initial composition and morphology.