Respiratory syncytial virus (RSV) is the most frequent cause of hospitalization for respiratory tract infection during the first 2 years of life. The optimal approach to management remains controversial. During the 1991 to 1992 RSV season RSV-infected children admitted to eight Canadian tertiary care pediatric centers were followed to: (1) assess the morbidity and mortality attributable to RSV infection among hospitalized patients with and without known risk factors for severe disease; and (2) assess regional variation in the management of RSV infection. Of 529 RSV-infected patients 69% (363) had one or more of the risk factors for severe disease and the remaining 31% (166) had none. There were significant differences (P < or = 0.01) between the high and low risk groups, respectively, for: intensive care unit admission (27%, 2%), assisted ventilation (14%, 0.6%), ribavirin therapy (20%, 2%), supplemental oxygen (75%, 34%), antibiotic therapy (69%, 58%) and length of hospital stay > or = 7 days (39%, 6%). Among low risk patients, centers varied significantly (P < or = 0.01) in the use of systemic corticosteroids (from 3 to 69% of patients), supplemental oxygen (13 to 74%), bronchodilators (68 to 93%) and ribavirin (0 to 10%). The observed regional variation in management of hospitalized children with RSV infection has implications for both the costs of hospital care and the conduct of multicenter trials of ribavirin and other therapies for RSV infection.