Fundamental and clinical studies were carried out on ceftazidime (CAZ) in the perinatal period, and the results obtained were summarized below. Following bolus intravenous injection of CAZ 2 g, maternal serum concentrations of CAZ were as high as 145.3 +/- 17.2 micrograms/ml (mean +/- S.D.) at about 10 minutes, and then gradually decreased to 46.7 micrograms/ml at 2 hours, 5.31 micrograms/ml at 5 hours and 4 minutes, and 1.54 micrograms/ml at 11 hours and 10 minutes. The CAZ was detected in umbilical cord serum immediately after the administration, and concentrations were 31.0 +/- 1.54 micrograms/ml at about 10 minutes. Although the concentrations gradually decreased thereafter, they were higher than those in maternal serum at 3 hours and later and was 3.00 micrograms/ml at 11 hours and 10 minutes. The CAZ was detected in amniotic fluid a little later than in umbilical cord serum, and concentrations of CAZ in amniotic fluid were as low as 1.50 +/- 0.67 micrograms/ml at about 10 minutes after the administration. Concentrations then gradually increased to 12.8 micrograms/ml at 2 hours and 26.5 micrograms/ml at 5 hours and 4 minutes, and even at 11 hours and 10 minutes, they were as high as 14.2 micrograms/ml. The above results demonstrated that the transfer of CAZ through placental barrier was very rapid and satisfactory. Also, CAZ showed good transfer into amniotic fluid, as well as sufficient retention, and was considered to be an effective antibiotic for prophylaxis of both fetal infections and amniotic fluid infections.(ABSTRACT TRUNCATED AT 250 WORDS)