A series of biodegradable random unsaturated/saturated poly(ether ester amide)s copolymers (USPEEAs) were synthesized by an active solution polycondensation of unsaturated and saturated dicarboxylic acid-based diester monomers with diamine salts of phenylalanine and saturated oligo(ethylene glycol) (OEG). These USPEEA copolymers were obtained with fairly good yields in DMA solvent. The chemical structures of the USPEEA copolymers were confirmed by both IR and NMR spectra. The molecular weights (M-n and M-w) of USPEEAs measured by GPC ranged from 3 to 27 kg/mol with the molecular weight distribution (MWD) ranging from 1.52 to 2.13. USPEEA copolymers obtained had T, lower than that of the pure UPEEAs but higher than that of pure saturated poly(ether ester amide)s (SPEEA). An increase in the unsaturated component in USPEEAs led to an increase in their T-g. A preliminary in vitro biodegradation property of USPEEA copolymers were investigated in both pure PBS buffer and alpha-chymotrypsin solutions. The USPEEA copolymers showed a pronounced weight loss in enzyme solutions, but a smaller weight loss in a pure PBS. The biodegradation rates of USPEEA copolymers in of-chymotrypsin solution were much slower than those of pure PEEAs. Therefore, upon adjusting monomers feed ratio, USPEEA copolymers could have controlled chemical, physical, and biodegradation properties. (C) 2008 Wiley Periodicals, Inc.