The authors have carried out the laboratory and clinical studies of T-1982 (cefbuperazone). The results were as follows: The sensitivity was estimated by the plate dilution method on 28 strains of S. aureus 26 strains of E. coli, 27 strains of K. pneumoniae, 25 strains of S. marcescens and 14 strains of Proteus sp. isolated from patients. The distribution of susceptibility of S. aureus was 1.25-25 micrograms/ml and the peak of distribution was 12.5 micrograms/ml. The strains of 84.6% of E. coli were inhibited at concentration of less than 0.39 micrograms/ml. The strains of 77.8% of K. pneumoniae were inhibited at concentration of less than 0.2 microgram/ml. The strains of 96% of S. marcescens was inhibited at concentration of less than 3.13 micrograms/ml. The distribution of susceptibility of Proteus sp. was 0.39-25 micrograms/ml. T-1982 was given to intravenous administration for 5 minutes and drip infusion for 30 minutes a single dose of 20 mg/kg of T-1982 to 2 and 2 children respectively. After intravenous administration of T-1982, the mean serum level was peak 88.4 +/- 8.7 micrograms/ml at 15 minutes, 52.5 +/- 2.7 micrograms/ml at 1 hour, 4.6 +/- 0.15 micrograms/ml at 6 hours respectively. Half-life was 89 minutes. And after drip infusion of T-1982, the mean serum level was 75.5 +/- 3.5 micrograms/ml at 30 minutes and 3.1 +/- 0.6 micrograms/ml at 6.5 hours respectively. Half-life was 82 minutes. The mean urinary excretion rate was 94.7%, 57.4 +/- 11.0% up to 6 hours after intravenous administration and drip infusion respectively. T-1982 was effective in 13 cases out of 13 cases with bacterial infections. No side effects were observed except for 1 case with elevation of serum GOT, 1 case with elevation of serum GPT and 2 cases with eosinophilia.