This open investigation evaluated twice daily administration of netilmicin in infants and children with systemic infections. Thirty-four patients aged 2-41 months, were enrolled; 28 and 34 were evaluable for efficacy and safety, respectively. Netilmicin was administered intravenously or intramuscularly every 12 h at a dosage of 2.0-4.4 mg/kg (mean 3.5 mg/kg) for 5-15 days (mean 11 days). Throughout the trial, signs and symptoms of infection were evaluated in conjunction with laboratory data to determine patients' clinical response; specimens from appropriate sites were cultured to determine bacteriological response; and laboratory tests were performed to monitor haematopoietic, hepatic and renal functions. Peak and trough serum netilmicin levels were measured during treatment. Clinical responses included complete resolution in 26/28 (93%) patients, improvement in 1/28 (4%) and failure in 1/28 (4%). Bacteriological responses included elimination of 34/36 (94%) pathogens and persistence of 1/36 (3%); response was indeterminate for 1/36 (3%). Peak serum netilmicin levels of 5.1-14.1 micrograms/ml and trough serum netilmicin values of 0.1-1.5 micrograms/ml remained within acceptable ranges during treatment. No clinically significant changes in haematopoietic, hepatic and renal functions were evident during the trial. Untoward reactions were limited to redness and/or induration at the administration site in 4/34 (12%) patients.