Nosocomial infections in infants and children were prospectively studied in the general wards of a hospital serving a developing community. Of 1350 admissions in 5 months, 193 (14.3%) developed 302 infections (22.4/100 admissions). The major risk factors were malnutrition, age less than 2 years and prolonged hospitalization. The most common sites of infection were the lower respiratory and gastrointestinal tracts. The most frequently isolated organisms were Staphylococcus aureus and Klebsiella species and the site of most frequent isolation was the lower respiratory tract for which the method most commonly used was endotracheal aspiration. Seventy percent of isolates were resistant in vitro to conventional antibiotics. Thirty-one percent of infections developed while the patient was awaiting a diagnostic procedure or waiting to be sent home. During the study period 60 patients (4.4% of admissions) were admitted with a nosocomial infection acquired elsewhere (31 at this hospital and 29 from other hospitals). Measles and its complications accounted for 28 of these cases and 7 deaths. This study provides information on nosocomial infections in children from a developing community.