SY5555 dry syrup (powder to be dissolved before use) was clinically used in pediatric patients. The following results were obtained: 1. The subjects were 6 pediatric patients including 1 case each with pharyngitis, tonsillitis, lacunar tonsillitis and impetigo contagiosa and 2 cases with scarlet fever. The drug was administered at a daily dose of 14.5-29.0 mg/kg divided into 3 dosages. The clinical results were excellent in 5 cases and good in 1 case with an efficacy rate of 100%. 2. Identified bacteria included 3 strains of Haemophilus influenzae, 2 strains of Streptococcus pyogenes and 1 strain of Staphylococcus aureus. Five strains were eradicated but 1 strain still remained with an bacteriological eradication rate of 83.3%. 3. No side effects were observed throughout the study period. In laboratory test results, elevated eosinophil count was observed in only 1 case. 4. Patients' compliance was good in general. 5. Based on the results mentioned above, the drug was considered to be a useful new oral antibiotic in the pediatric field.