A virus was identified in 464 out of 1,212 patients, 8 days to 16 years of age, who were admitted to the hospital in Paris during a 3 year period. Respiratory syncytial virus (RSV) was found in 428 patients, 74% were younger than 6 months with bronchiolitis, and 6% were older than 2 years. RSV was the first virus isolated in all patients and in those with pneumonia or asthma. The low number of admissions due to parainfluenzae viruses is characteristic of this area compared to other countries.