Tissue concentrations of cefamandole (CMD) one hour after the end of 2 g/30 approximately 60 minutes drip infusion were 7.3 approximately 13.1 microgram/g in uterus, ovary and oviduct. These concentrations were higher than MICs of 70 approximately 100% of causative organisms, including Staphylococcus aureus, Escherichia coli, Klebsiella, Proteus mirabilis, Enterobacter and Citrobacter, isolated from the infections in the field of obstetrics and gynecology. 2) CMD was administered to 14 patients with moderate infections in the field of obstetrics and gynecology at a daily dose of 4 g for 5 approximately 7 days. The overall clinical efficacy obtained was as follows; excellent in 7 cases (50%), good in 3 cases (21%) and poor in 4 cases (29%). 3) Antimicrobial activity of CMD against causative organisms resembled that of CEZ. 4) No adverse effects and abnormal laboratory findings were observed. From the above, we considered that CMD was an effective and safe antibiotic against infections in the field of obstetrics and gynecology.