We made fundamental and clinical studies of a new cephalosporin derivative, cefpimizole (AC-1370). AC-1370 was relatively efficiently transferred into the uterine adnexa; in other words, it was as well transferred into the tissues as the other cephalosporin derivatives. There seemed to be no specific relation between its blood level and its level in any tissue. In 1 patient treated with AC-1370 for postoperative infection, clinical findings, WBC and CRP improved: the drug was evaluated as effective. Neither hepatic nor renal function was impaired in the patients treated with AC-1370 in the fundamental and clinical studies of the drug.