Fundamental and clinical studies on a new cephalosporin antibiotic, cefpiramide (CPM), was carried out under a joint study program, in order to evaluate the usefulness of the drug in treating infection of the female genital organs. The results obtained were as follows: CPM was readily transported to female genital organ tissues, and the concentrations of the drug exceeded 35 micrograms/g in various organ tissues in about 1 hour, following intravenous injection of 1 g. A level of more than 2 micrograms/g was maintained even 14 hours after the injection. The transport of CPM to various tissues was also studied following intravenous drip infusion of 1 g for 1 hour. The concentrations in tissues were slightly low but similar to those following intravenous injection. The peak concentration of the drug in the dead space exudate was 3.1-20.4 micrograms/ml, following intravenous injection and intravenous drip infusion of 1 g. The MIC80 of CPM were 3.13-12.5 micrograms/ml against S. aureus, Klebsiella sp., P. mirabilis and P. aeruginosa. Clinical effects of CPM were analyzed in 158 patients, including 56 cases with intrauterine infection, 37 cases with intrapelvic infection, 22 cases with external genital infection, 31 cases with adnexitis, 6 cases with postoperative wound infection and 6 cases with other infections. Excellent response was seen in 28 cases (17.7%), good response in 120 (75.9%) poor response in 10 (6.3%). The rate of response was calculated as 93.7%. Safety of the drug was analyzed in 258 patients, and side effects occurred in 4 (1.6%). Of these 4 patients, rash was in 1 patient, heat sensation in 1 patient, nausea in 1 patient and rash accompanying edema in 1 patient. Abnormal values in clinical laboratory findings were seen in 7 patients. Elevations of transaminase were seen in 5 patients and decrease of platelet was seen in a patient, and then elevations of transaminase with decrease of platelet was seen in a patient, and no other changes of particular note appeared.