Imipenem-cilastatin was evaluated for tolerability and efficacy in a multicenter open, noncomparative trial involving 178 infants and children with bacterial infections. Imipenemcilastatin was administered in total daily dosages of 100 mg/kg for patients up to 3 years of age and 60 mg/kg for those more than 3 years of age. Favorable clinical response was achieved in 98 of 100 patients judged evaluable for efficacy. Adverse effects were generally mild and reversible and included diarrhea alone or with vomiting (5.1%), irritation of intravenous infusion site (3.3%) and rash (2.2%). Changes in laboratory test values reported most frequently were thrombocytosis (8.9%), elevations in aspartate aminotransferase (7.9%) and alanine aminotransferase (5.6%) and eosinophilia (8.4%). This safety profile appears to be comparable to that of other beta-lactam antibiotics. Moreover imipenem-cilastatin was effective in infections caused by a broad spectrum of pathogens that include Haemophilus influenzae, Staphylococcus aureus, P. aeruginosa and anaerobes. These attributes suggest that imipenem-cilastatin should be safe and effective in selected pediatric patients.