Abstract. Plastic bronchitis (PB) is a rare condition known to be associated with many pulmonary, cardiac, and systemic diseases. It is characterized by the formation and expectoration of peculiar long branching casts of the bronchial tree with rubber-like consistency causing airway obstruction. PB does not present as early as the neonatal or immediate post-neonatal period [1]. However; the condition is probably underestimated, as the casts with their specific ramifications are sometimes difficult to recognize. PB has been increasingly reported in relation to some cardiosurgical procedures, notably those bypassing the right ventricle via connecting the systemic venous vessels to the pulmonary artery (e.g., Fontan and Glenn) [2]. Being mainly composed of laminated mucin, little fibrin, but usually no inflammatory cells, the bronchial casts associated with cardiosurgical procedures are classified as type-II (acellular) casts, while type-I (inflammatory) casts, mostly made of fibrin, a small amount of mucin and dense eosinophilic infiltrate, usually complicate pulmonary disorders [3]. Although inflammatory mechanisms have not been considered for cases of congenital heart disease, small numbers of infiltrating cells, including eosinophils usually exist in the casts. We report on a preterm baby with pulmonary atresia and intact interventricular septum, that was not detected antenatally, who presented with cyanosis after iatrogenic induction of duct closure by a non-steroidal anti-inflammatory drug, ibuprofen. Prostaglandin E1 infusion commences to reverse duct closure and keep its patency. A series of cardiosurgical procedures undertaken to improve oxygenation were complicated by an unusual cause of airway obstruction, PB with inflammatory cellulartype casts.