AbstractPulmonary arterial thrombosis is an extremely rare occurrence in the neonatal population. We describe a 2-week-old female neonate who presented in critical condition with severe cyanosis and dehydration and was found to have a large thrombus in the main branches of the pulmonary arteries. She was successfully treated with surgical embolectomy. Pulmonary arterial thrombosis should always be considered in the differential diagnosis of a dehydrated neonate presenting with severe cyanosis and evidence of pulmonary hypertension.