Three poly(beta-aminoester)s with pendant primary amines were synthesized by Michael addition of N-Boc-protected diamine to 1,4-butanedioldiacrylate, followed by removal of N-Boc-protective group under anhydrous acidic conditions. The degradation rate of poly(beta-aminoester)s with pendant primary amines is dependant on their side-chain structures and pH value of incubation buffer. The degradation in basicenvironments is much faster than in acidic environments. The degradation of poly(beta-aminoester) with pendant primary amine involves intramolecular/intermolecular amidation and hydrolytic degradation. Under physiological conditions, the intramolecular/intermolecular amidation ofpoly(beta-aminoester) plays an important role in the polymer degradation. Polymers 1ae1c show significant buffer capacity at pH 4e10. Thecytotoxicity of polymer 1a is much higher than that of polymers 1b and 1c.