Cefazolin ethoxycarbonylethyl ester (CFZ-ET) was synthesized to improve oral absorption and bioavailability of the parent drug by esterification of sodium cefazolin (CFZ-Na). The successful synthesis of CFZ-ET was identified with analysis of UV spectra, FT-lR spectra and NMR spectra. Partition coefficient studies showed that CFZ-ET was more lipophilic than CFZ-Na and the ester was hydrolyzed into the parent drug in vivo. Although CFZ-ET did not have antimicrobial activity in vitro, the plasma taken after the oral administration of CFZ-ET had antimicrobial activity. Based on above observations, CFZ-ET might be rapidly hydrolyzed to CFZ in the body. Therefore, it may be concluded that CFZ-ET could be a novel prodrug of CFZ which can improve the bioavailability of CFZ-Na.