T-1982 (cefbuperazone), a new injectable cephamycin antibiotic, was studied for its antibacterial activity, concentration in serum and urine, penetration into cerebrospinal fluid (CSF) as well as clinical application. The following results were obtained. 1. Antibacterial activity: The susceptibilities of clinically isolated K. pneumoniae, E. coli and E. cloacae to T-1982 were superior to those of CEZ CMZ, and ABPC. T-1982 seemed to be useful for various infections due to Gram-negative rods. 2. Concentration in serum and urine: Subjects were 10 children with congenital heart failure but no abnormal renal and liver functions. T-1982 was given intravenously to 3 groups at 200 mg/kg by one shot (4 cases), 20 mg/kg by 1 hour drip infusion (3 cases) and 10 mg/kg by 1 hour drip infusion (3 cases). The half-lives were 60, 78 and 85 minutes, respectively. 3. Penetration into cerebrospinal fluid: Three children with malignant tumor were injected 20 mg/kg intravenously. A small amount of T-1982 was penetrated into CSF. 4. Clinical efficacy: T-1982 was administered daily 40-116 mg/kg t.i.d. or q.i.d. for 2-14 days to 17 children comprising 1 bronchopneumonia, 1 bronchitis, 4 tonsillitis, 1 lymphadenitis, 1 sepsis, 1 pharyngitis, 1 impetigo, 1 acute sinusitis and 6 pyelonephritis. Clinical efficacy was excellent in 10, good in 2, fair and poor in 3, and the efficacy rate was 70.6%. Bacteriological effect was as follows; eradicated in 9 cases and unknown in 8 cases. As side effect, GOT and GPT elevations unrelated to the drug were observed in 2 cases. Other abnormal findings were not found. T-1982 seems to be safe antibiotic in the field of pediatrics.