We administrated cefodizime (40 mg/kg) to 13 patients with simple herniorrhaphy in the pediatric field and determined its concentrations in tissues and serums. The mean serum and tissue levels of cefodizime after administration were 43.1 +/- 13.3 micrograms/ml, and 23.1 +/- 6.4 micrograms/g, respectively, at 3 hours. Cefodizime concentrations of the tissue and serum were maintained at relatively high levels for many hours. The ratio of cefodizime concentrations in tissue to serum became high at 3 hours after administration, and this suggests that tissue concentrations decreased more slowly than serum levels, and cefodizime concentrations in tissue were maintained at fairly high levels over a long period. No side effects caused by cefodizime were observed. From pharmacokinetic and clinical observations, cefodizime appears to be a safe and effective injectable antibiotic for the treatment of infections in children.