The authors have carried out the laboratory and clinical studies of cefuroxime (CXM). The results were as follows: The sensitivity was measured by plate dilution method on 26 strains of S. aureus, 22 strains of E. coli and 24 strains of K. pneumoniae isolated from patients. The distribution of sensitivity of S. aureus was 0.78 approximately 3.13 micrograms/ml and the peak of distribution was 1.56 micrograms/ml. The distribution of sensitivity of E. coli was 1.56 approximately 50 micrograms/ml and the peak was 6.25 micrograms/ml. The growth of 79.2% K. pneumoniae was inhibited in concentration of less than 3.13 micrograms/ml. CXM was given intravenously for 30 minutes at a single dose of 20 mg/kg to 3 children. The serum mean levels of CXM were 99.0 +/- 10.6 micrograms/ml at 30 minutes, 18.0 +/- 10.7 micrograms/ml at 1 hour, 7.0 +/- 2.0, 2.2 +/- 0.6, 0.79 +/- 0.2 microgram/ml at 2, 4 and 6 hours after drip infusion for 30 minutes, respectively. Mean half life was 48 minutes. The mean urinary recovery rate was 96.2% up to 8 hours after administration. CXM was effective in 9 of 10 cases of bacterial infections. No side effect was observed except for 1 case with elevation of serum transaminase.