Growth and development were monitored for up to 42 months in nine neonates to whom ciprofloxacin, a fluoroquinolone, was given in the neonatal period at a dosage of 20 mg/kg/day. Ciprofloxacin was used only as a ¿life-saving' therapy in cases of sepsis produced by bacterial agents resistant to other antibiotics. Two other groups of nine neonates, matched by birth weight and gestational age, were studied as controls: one group with sepsis, which was effectively treated with cefotaxime and a group of healthy neonates. No statistically significant differences in growth and development between the groups were found during follow-up for 42 months. No osteoarticular problems or joint deformities were observed in the ciprofloxacin group. Ciprofloxacin appears to provide a therapeutic option as a ¿life-saving' therapy for newborns with sepsis produced by multiply resistant organisms.