Pharmacokinetic and clinical studies of ceftizoxime suppository (CZX-S) were performed in 10 children with the following results. CZX-S attained a peak serum concentration of 6.85 micrograms/ml 30 minutes after dosing with the drug 5.6 mg/kg (one suppository of CZX-S contains 250 mg of CZX in potency). The mean 6-hour urinary excretion rate in 4 children was 18.9%. The subjects consisted of 8 patients comprising 1 with pharyngitis, 3 with tonsillitis, 1 with gingivitis and 3 with urinary tract infection. The overall effect of CZX-S was "excellent" in 5 patients and "good" in 3, with an effectiveness rate of 100%. No side effects ascribable to CZX-S were encountered in any of the patients. A few patients complained of discomfort after the first or second insertion of the drug. However, the discharge of the suppository was as infrequent as 1.5% of the total 133 insertions. CZX-S is therefore well tolerated for clinical use in children. It is concluded that the unique suppository formulation of CZX-S is useful in the treatment of infections in children with heavy psychophysiologic disorders and in children who cannot take oral drugs because of severe vomiting.