Objective. We report post–mortem findings of a sudden death case of severe idiopathic pulmonary arterial  hypertension complicated by thromboembolism and review the relevant literature. Methods.  A 36 years old man was brought to Accident and Emergency ward of a 492 bedded zonal level hospital with history of sudden collapse.  The patient was a known case of Idiopathic pulmonary arterial hypertension and was under treatment. On arrival, he was unresponsive to therapy, and died suddenly. Results. Autopsy revealed presence of pulmonary arterial endoluminal thromboembolism grossly completely blocking the pulmonary arterial trunk, with features of pulmonary hypertension in the both lungs. The main pulmonary artery trunk wall show features of perivascular mononuclear inflammatory infiltrate. Conclusion. This appears to be rare reported case of pulmonary arterial hypertension complicated by thromboembolism of main pulmonary artery in association with large vessel perivascular inflammatory infiltrate.