Four cases of sudden unexpected death associated with pulmonary hypertension are described. In all cases, the presence of pulmonary hypertension had not been clinically detected. In each case, the underlying etiology of the pulmonary hypertension was different with one case each of occult adult congenital heart disease, pulmonary sarcoidosis, pulmonary tumour microembolism from gastric adenocarcinoma, and familial primary pulmonary hypertension. These cases indicate that the forensic pathologist must be aware of occult pulmonary hypertension as a cause of sudden unexpected death in a variety of age groups.