The single-dose pharmacokinetics of cefodizime were studied in ten hospitalized children aged between two and 15 years and weighing 12.5-26.2 kg. Six subjects received the drug (25 mg/kg) im and four received it iv. Cefodizime concentrations in blood and urine (iv dosage only) sampled up to 12h post dose were measured by microbiological assay and pharmacokinetic parameters were derived on the basis of a two-compartment open model. Peak serum concentrations were 131 +/- 22.7 mg/l (15 min post iv dose) and 54.8 +/- 17.8 mg/l (60 min post im dose). Mean T1/2 beta were 1.9 +/- 0.13 h (iv) and 1.88 +/- 0.25 h (im). Mean AUCs were 217.2 +/- 37.9 mg.h/l (iv) and 150.85 +/- 22.98 mg.h/l (im). Mean volumes of distribution were 7.6 +/- 2.5 l (iv) and 7.9 +/- 1.41 (im). Twelve hours after the iv administration the cumulative urinary excretion was 78-87% of the dose. The pharmacokinetic behaviour of cefodizime in children is thus similar to that of other compounds in this class.