The patterns and nature of a four-month epidemic of severe respiratory syncytial virus (RSV)-associated disease were analyzed using presenting, demographic, clinical, and therapeutic data. Of 218 infants with RSV infection admitted to Rainbow Babies and Childrens Hospital, 49 (22.4%), most born prematurely, entered the pediatric intensive care unit (PICU). Fluorescent antibody and/or enzyme-linked immunosorbent assay documented RSV infection. PICU patients underwent airway stabilization; 53.5% were intubated and evaluated for sepsis. Patients with positive bacterial cultures received antibiotics; 18% were given ribavirin. Patterns of infection included hypothermia, septic shock appearance, apnea, pneumonia, and wheezing due to bronchiolitis. The average age difference between patients with hypothermia (23.3 days) and those with pneumonia (11.2 months) was statistically significant. There were no significant differences in average age, gestational age at birth, number intubated, worst pH and PCO2, duration of intensive care, or treatment modalities between infants with bronchopulmonary dysplasia who received ribavirin and those who did not.