Cefozopran (CZOP) was administered via intravenous injection to 9 patients (ages ranging from 1 month to 13 years) with pediatric bacterial infections, at daily dose levels between 56.7 and 200 mg/kg, divided into 3 or 4 doses. The following results were obtained. 1. Eight patients, including 1 with purulent meningitis, 1 with sepsis, 3 with acute pneumonia and 3 with lymphadenitis, were treated and subjected to clinical evaluation. Clinical effects were excellent in 6 cases and good in 2, with an overall efficacy rate of 100%. One case with pyoderma was not evaluated because of a combined use of an external antibiotic. 2. Organisms suspected as pathogens included 5 strains: 3 strains of Haemophilus influenzae, 1 strain of Staphylococcus aureus and 1 of Escherichia coli. Bacteriologically, all the strains were eradicated. 3. Side effects or abnormal laboratory test results were observed in 4 cases; wheal in 1 case, elevated GOT and GPT in 2 cases and eosinophilia in 1 case. 4. From the results described above, we considered that CZOP would be an effective drug for use in pediatric bacterial infections.