Cefminox (CMNX, MT-141) was studied both fundamentally and clinically with following results: In the treatment of 3 cases of Bartholin's abscess, 2 cases of pyometra, and 1 case each of bartholinitis, inflammation of the pelvic dead space, retroperitoneal abscess and pelvic peritonitis, CMNX was administered at a dosage of 1 g. The global clinical results were rated as good in 9 cases. From these findings it is considered that CMNX is promising as an antibiotic with extremely high efficacy for infections of the field of obstetrics and gynecology. Furthermore, since in none of our cases side effects or laboratory abnormalities were observed, CMNX is considered to be a drug with high efficacy and safety. In 5 cases received 1 g of CMNX intravenously, concentrations of the drug in the serum and tissues of internal genital organs were determined. CMNX was maintained at concentrations higher than 20 micrograms/ml for the serum and 10 micrograms/g for each tissue studied. In the pelvic dead space exudate 10 to 20 micrograms/ml of the drug was still detected even at 8 hours after the administration. These results obtained by our fundamental study support the efficacy of CMNX demonstrated in the clinical part of our study.