Cefdinir (CFDN, FK482) granules, a new oral antibiotic for children, were given to children with infections. The results obtained are summarized as follows. 1. The plasma level of CFDN peaked at 0.38-0.88 microgram/ml in 2-3 hours after administration of the drug at a dose of 3 mg/kg. Meanwhile, the plasma level peaked at 1.85 micrograms/ml in 3 hours after administration of 6 mg/kg. The plasma level was higher in the 6 mg/kg group than that in the 3 mg/kg group, thus a dose response was clearly observed. 2. The 8 hour urinary excretion accounted for 10.3-17.4% of administered amount of the drug in children with 3-6 mg/kg dosage. 3. CFDN granules were administered to a total of 42 children with upper or lower airway infections or with urinary tract infections at daily doses of 9.0-20.7 mg/kg in 3 divided portions. The clinical efficacy was "excellent" in 28 patients, "good" in 13, and "fair" in 1, hence an efficacy rate of 97.6% was obtained. 4. Bacteria identified from various diseases were 29 strains of 9 species, and the eradication rate was 82.8%. 5. No. side effects were noted in any of the children. Laboratory test results showed an abnormality in 1 case each with a rise of platelet count and eosinophilia.