T-1982 (cefbuperazone), a new cephamycin antibiotic, was basically and clinically studied in the field of pediatrics, and the following results were obtained. 1. The antibacterial activity of T-1982 was compared with that of CEZ, CMZ and ABPC. T-1982 was more active than the other drugs against Gram-negative bacteria, the sensitivity of E. coli (22 strains), K. pneumoniae (18 strains), P. mirabilis (19 strains), P. vulgaris (4 strains), P. morganii (5 strains) and K. oxytoca (4 strains) distributing less than 0.39, 0.1, 1.56, 0.39, 6.25 and 0.2 microgram/ml, respectively. Two of 3 strains of C. freundii were inhibited by 12.5 micrograms/ml. Against Gram-positive bacteria, the activity of T-1982 was inferior to that of the other drugs. S. pyogenes (28 strains) were inhibited by 0.78 microgram/ml or less, but the sensitivity of S. aureus (34 strains distributed 12.5-100 micrograms/ml). 2. T-1982 was administered to each 3 children at a dose of 20 mg/kg by one shot intravenous injection or 1 hour drip infusion, or at dose of 40 mg/kg by 1 hour drip infusion. The mean serum levels at 0.25, 0.5, 1, 2, 4 and 6 hours after one shot intravenous injection of 20 mg/kg were respectively 74.3, 56.3, 42.3, 17.6, 5.7 and 1.2 micrograms/ml with the mean half-life of 1.01 hours. The values were 32.9, 50.0, 73.7, 27.5, 12.4 and 4.5 micrograms/ml and 1.31 hours by intravenous drip infusion of 20 mg/kg and 50.4, 104.7, 136.3, 62.3, 18.6 and 6.9 micrograms/ml and 1.16 hours by intravenous drip infusion of 40 mg/kg. The mean urinary recovery rates within 6 hours were 47.7, 67.6 and 60.9%, respectively. 3. Treatment with T-1982 was made in 28 cases of pediatric infections; 1 case of acute bronchitis, 19 cases of acute bronchopneumonia or lobar pneumonia, 2 cases of acute purulent cervical lymphadenitis, 4 cases of acute pyelonephritis and each 1 case of subcutaneous abscess and suspected bacterial endocarditis. The clinical responses assessed in 27 cases were excellent in 21 cases, good in 5 cases and poor in 1 case, the efficacy rate being 96.3%. Bacteriologically, 2 strains of S. aureus, 3 strains of S. pneumoniae, 4 strains of H. influenzae, 2 strains of E. coli and 1 strain of P. mirabilis were eradicated. One strain of S. faecalis was reduced. No side effects were observed in any cases. Slight elevation of GOT and GPT and that of GOT were noted in each 1 case.