For analysis of clinical features and outcome of hospitalized infants with respiratory syncytial virus lower respiratory tract infection, was carried out. Cross-sectional study with 89 infants, hospitalized in two public hospitals during the 1997 and 1998 RSV seasons, in Rio de Janeiro city. Nasopharyngeal secretions were obtained and specimens processed for viral antigens detection by indirect immunofluorescence assay with the use of anti RSV, anti-influenza A and B and anti parainfluenza type 3 monoclonal antibodies. Patients were allocated into three diagnostic groups: bronchiolitis or wheeze bronchitis (n = 44); Pneumonia (n = 26) and bronchiolitis or wheeze bronchitis and pneumonia (n = 19). Positivity for RSV was found in 42 (47.1%) patients. More days of hospitalization were seen in 1997 in comparison with the follow year (p >0.05). No clinical differences were found between RSV positive and negative children. The sensitivity and specificity for wheezing concerning the isolation of RSV were, respectively, 85% and 65%. RSV was the major cause of LRTI in hospitalized infants.