Several case-reports and small series suggest a causal relationship between human immunodeficiency virus (HIV) infection and pulmonary hypertension. We report on a HIV seropositive man with a high and stable CD4 lymphocyte count (+/- 600/mm3) who developed severe pulmonary hypertension, not attributable to other known causes. This case report underscores the fact that the degree of immunosuppression secondary to the HIV-infection seems to be of little relevance in the pathophysiology of the syndrome. HIV-infected patients with dyspnoea, not related to pulmonary infection, with exercise intolerance, syncope or precordial pain should receive an electrocardiogram and echocardiographic assessment. The exact pathogenetic mechanism of this rapidly progressive disease and whether anti-viral therapy should be promoted is still under investigation.