T-1982 (cefbuperazone), a new cephamycin antibiotic, was studied for its MICs against clinical isolates, transfer into uterine tissues and clinical efficacy in the field of obstetrics and gynecology. The following results were obtained. The MICs of T-1982 were measured against 397 strains of 13 species. In antibacterial activity, T-1982 was equal to CTT but inferior to CMZ against Gram-positive bacteria. Against Gram-negative bacteria, T-1982 was superior to CEZ and other cephamycin antibiotics, i.e. CMZ and CTT. The activity of T-1982 was almost equal to that of CMZ and superior to that of CTT against B. fragilis. T-1982 concentrations in various uterine tissues attained the peaks of 16.8-35.9 micrograms/g at 34 minutes after intravenous administration of 1 g, the tissue/serum ratios being 34-72%. The tissue concentrations were about 3-4 micrograms/g even at 5-5.5 hours after administration. T-1982 was intravenously administered at a dose of 1 g twice daily to 5 cases with obstetrical and gynecological infections. All the cases responded to the therapy. Elevated GOT and GPT were observed in 1 case, but they returned to normal on 8 days after the therapy.