A 15-year-old boy with hypoplastic left heart syndrome experienced plastic bronchitis 9 years after completion of a nonfenestrated lateral tunnel Fontan. Despite cardiac catheterization with coil embolization of collateral vessels and initiation of a pulmonary toilet regimen, including aerosolized tissue plasminogen activator, he continued to expectorate large acellular-mucinous casts. Finally, after optimization of cardiac function with the addition of carvedilol, the expectorated casts decreased in number. This report reviews pathophysiology of plastic bronchitis cast formation and therapy in the context of this late presentation after Fontan. © 2007 Springer Science+Business Media, LLC.