The Palivizumab Outcomes Registry collected data on 19,548 high-risk infants who received > or =1 dose of palivizumab and followed prospectively from 2000 through 2004. Ninety-one children with cystic fibrosis (CF) were identified who received palivizumab off label. None of the infants with CF who received prophylaxis was hospitalized as a result of respiratory syncytial virus lower respiratory tract infection. Evaluations of palivizumab use in infants with CF could be warranted.