Plastic bronchitis is characterized by marked obstruction of the large airways by bronchial casts. We reviewed our experience and the literature to determine whether mortality rates are determined by underlying disease or cast type. We present 3 children with obstructive bronchial casts. One 3-year-old patient with Noonan's syndrome developed respiratory failure following surgery for tetralogy of Fallot requiring support with extracorporeal membrane oxygenation (ECMO) the first such case. There were 42 cases in the literature of children with plastic bronchitis. Casts may be divided into two types. Type I casts are inflammatory, consisting mainly of fibrin with cellular infiltrates, and occur in inflammatory diseases of the lung. Type II, or acellular casts, consist mainly of mucin with a few cells, and usually occur following surgery for congenital cardiac defects. Patients categorized by underlying disease included 31% with asthma or allergic disease, 40% with underlying cardiac defects, and 29% with other diseases. Mortality was 16%, but increased to 29% in patients with cardiac defects. Deaths occurred as long as 1 year after surgical repair for underlying defects. There were no deaths in patients with asthma. Life-threatening events were statistically higher in patients with cardiac defects (41%) than in those with asthma (0%, P = 0.02). Higher mortality in patients with type II casts compared to type I casts did not reach statistical significance (28% vs. 6%; P = 0.06). In conclusion, patients presenting with plastic bronchitis are at high risk for serious complications, especially with underlying cardiac disease. Copyright 2002 Wiley-Liss, Inc.