We have studied the clinical efficacy and pharmacokinetics of cefuroxime in 3 children aged 5, 7 and 10 months who were suffering from meningitis due to Haemophilus influenzae group b (beta-lactamase producers). The MICs of chloramphenicol against these three beta-lactamase-producing H. influenzae isolates were 8, 3.1 and 16 micrograms/ml, and those of cefuroxime were 0.25, 0.5 and 0.12 microgram/ml, respectively. The dosage of cefuroxime was 100 mg/kg/day divided in four 6-hourly intravenous doses for 15 days, and 10 mg given intrathecally every 48 h. Blood and spinal fluid levels were determined by microbiological assay. All the 3 children had excellent clinical and bacteriological responses with negative spinal fluid cultures after 48 h of treatment.