Basic and clinical evaluations of cefroxadine were carried out in children, and the following results were obtained. 1. Cefroxadine 20 mg/kg was administered to 9 children with heart disease for the prophylaxis against infections before undergoing cardiocatheterization and cardioangiography, and serum levels were determined. Peak levels reached after 30 minutes in 4 of the 9 cases, with a mean peak level of 22.5 mcg/ml and after 1 hour in 5 cases, with a mean peak level of 16.2 mcg/ml. Half life was 3.1 hours in the former group in a 6-hour blood sampling (1.04 hours in a 2-hour sampling) while in the latter group it was 1.37 hours. 2. Clinical responses were evaluated in 56 children comprising 23 cases of pharyngitis, 8 of tonsillitis, 13 of scarlet fever, 10 of urinary tract infections and 2 of impetigo. Fifty of these cases had excellent and good responses showing a efficacy rate of 89.3%. 3. From 42 of the cases, 43 strains were isolated as causative organisms. Major organisms included 27 strains of S. pyogenes, 9 of E. coli and 3 of S. aureus. As for bacteriological responses, all strains were eradicated. 4. No severe side effects were observed except for diarrhea of 1 cases and eosinophilia of 2 cases. Furthermore, no children refused to take cefroxadine dry syrup.