• Aerosolized ribavirin was administered to 12 infants with bronchiolitis who were receiving mechanical ventilation. All patients had a history of cardiac or pulmonary disease and developed severe respiratory failure during their infection. We developed a method for ribavirin administration and patient monitoring that included timed circuit valve and tubing changes to avoid obstruction by precipitated drug, frequent endotracheal tube suctioning, and constant observation of the patient and ventilator. All patients were successfully treated. We conclude that ribavirin can be safely administered to infants receiving mechanical ventilation.