A novel branched poly(anhydride-co-glycerol) was synthesized by introducing glycerin into a poly(sebacic anhydride-co-ethylene glycol) system via melt condensation without catalyst. The nuclear magnetic resonance spectroscopy (NMR) analysis showed that the reaction between the hydroxyl group on glycerin and the sebacic anhydride pre-polymer was completed without any hydroxyl group remaining. In addition, with more glycerin introduced, intramolecular chain reaction became more remark-able. This resulted in the production of more cyclic chains and lower molecular weight species that hinder the crystal growth of sebacic anhydride chain segments. This in turn decreases melting temperature of sebacic anhydride chain segments in these synthesized materials. (C) 2003 Wiley Periodicals, Inc.