Iatrogenic illness may be an important determinant of the need for pediatric intensive care. We prospectively evaluated consecutive admissions to a pediatric ICU (PICU) over two time periods totaling 6 months. Twenty-five (4.6%) admissions were necessitated by iatrogenic illnesses. Drug-induced conditions accounted for eight (32%) of the iatrogenic patients, and complications of medical-surgical acts accounted for 17 (68%). Diagnoses included six respiratory failures due to seizure medications, six chronic upper airway complications of neonatal intensive care, four posttonsillectomy and postadenoidectomy complications, two chronic postcardiac surgery complications, two cardiac catheterization complications, and five miscellaneous conditions. One (3.7%) patient with iatrogenic illness died. As a group, patients with iatrogenic illness were at a risk of dying similar to other patients. We conclude that iatrogenic illness is a significant cause of PICU admission.