A study on the copolymerization of glycolide with lactide and glycolide with epsilon-caprolactone was performed in the presence of zirconium (IV) acetylacetonate at moderate temperatures (100 degrees and 150 degrees C). Zirconium acetylacetonate appeared to be an efficient initiator of copolymerization. The obtained polymers were characterized by high molecular weights. Considerable influence of transesterification on the polymer chain microstructure was found.