A new class of biodegradable polymers that show promising characteristics for orthopedic applications was investigated. This study examines aspects underlying the polymer erosion of poly[trimellitylimidoglycine-co-1,6-bis(carboxyphenoxy)hexane] and poly[pyromellitylimidoalanine-co-1,6-bis(carboxyphenoxy)hexane]. Copolymer degradation was studied by examining the anhydride bond hydrolysis and copolymer composition by IR and NMR spectroscopy. Hydrolysis of the anhydride bonds occurred much faster than did the dissolution of the hydrolyzed products, leading to the formation of two distinct erosion zones. The two erosion zones were observed by light and scanning electron microscopy with erosion originating at the surface and moving to the center of the polymer samples.