Medical records of 261 hospitalized patients less than 1 year old with documented respiratory syncytial virus (RSV) infection were reviewed to determine the incidence of RSV-associated apnea and the accompanying risk of subsequent apnea or death. Apnea in association with RSV infection occurred in 18% of the infants. Premature birth and a young postnatal age were risk factors for development of apnea with RSV disease. Apnea of prematurity appeared to be a significant risk factor for RSV apnea development in infants with a gestational age of 32 weeks or less at birth, but infants with RSV apnea did not appear to be at risk for subsequent apnea. These results suggested that in hospitalized infants, RSV apnea may be related to immaturity of respiratory drive. Two of the 48 infants with RSV apnea subsequently died during the first year of life.