Twenty nine children were treated with cefpodoxime proxetil (CPDX-PR, CS-807) and the clinical efficacy and side effects were evaluated. Ages of the patients ranged from 2 months to 10 years. Dose levels of CPDX-PR ranged from 7.5 to 12.0 mg/kg/day for 5 to 12.7 days. The 29 patients included 9 tonsillitis, 2 otitis media, 5 scarlet fever, 3 bronchopneumonia, 1 lymphadenitis, 8 urinary tract infections and 1 staphylococcal scalded skin syndrome, and they were evaluated for the clinical efficacy of CPDX-PR. Results were excellent in 21 and good in 8 patients. Out of the 29 patients, 3 cases showed diarrhea and 2 cases showed elevated GOT and GPT. The pharmacokinetics of CPDX-PR was studied in 9 patients whose ages ranged from 1 to 9 years. The serum peak concentrations of CPDX in 5 patients were between 1.37 and 4.10 micrograms/ml (mean: 2.53 micrograms/ml) at 1 to 6 hours after dosing 3 mg/kg before meals. Those of 4 patients ranged 3.29 to 4.88 micrograms/ml (mean: 4.36 micrograms/ml) at 2 hours after administering 6 mg/kg before meals. Portions of CPDX excreted into urine within 6 hours ranged from 20.3 to 34.3% (mean 27.1%) in 5 patients who were given 3 mg/kg, and ranged from 24.1 to 65.7% (mean 41.1%) in 4 patients given 6 mg/kg.