Ceftazidime ( CAZ ), a new cephalosporin antibiotic, was fundamentally and clinically studied. The following results were obtained. Serum and internal genital tissue levels of CAZ were measured following intravenous drip infusion of 1 g for 30 minutes. Serum levels of more than 10 micrograms/ml and tissue levels of more than about 7 micrograms/ml were maintained after 2 hours to 2 hours and 30 minutes, respectively. Favourable transfer of CAZ into the pelvic dead space exudate was observed. The exudate level attained its peak of 31.54 micrograms/ml on average at 2 hours and was 16.8 micrograms/ml on average even at 8 hours after intravenous drip infusion. A total of 6 cases comprising 1 of adnexitis, 2 of pyometra, 1 of endometritis and 2 of parametritis was treated with CAZ at a dose of 0.5 approximately 2.0 g twice daily by intravenous injection or intravenous drip infusion. The clinical response was excellent in 1 case, good in 4 cases and poor in 1 case. Abnormal laboratory findings and side effects due to the drug were not noted.