The synthesis and characterization of degradable poly[bis(ethyl 4-aminobutyro)phosphazene] is described. This polymer was prepared by a two-step reaction procedure. First, poly (dichlorophosphazene) was synthesized by thermal polymerization of the cyclic trimer hexachlorocyclotriphosphazene. In the second stage, the poly (dichlorophosphazene) structure was converted into the amino acid ethyl ester derivative by a nucleophilic substitution reaction. Both polymeric structures were characterized by FTIR, P-31 NMR, SEM and viscosity measurements. Degradation studies were carried out with 100 mum polymeric films in phosphate buffered saline at 37degreesC. Mass loss measurements showed that, on day 25, 70% of the original mass was lost. In addition, non-toxic behavior of the polyphosphazene films was shown by cytotoxicity tests conducted in cell culture media. (C) 2002 Published by Elsevier Science B.V.