Primary pulmonary hypertension is usually considered a disease of younger adults. We reviewed the natural course of primary pulmonary hypertension in patients aged 65 years or greater. During an 8-year period, 63 elderly patients were discharged from our hospital with a diagnosis of pulmonary hypertension. In eight instances, an elevated mean pulmonary arterial pressure (greater than 25 mm Hg) could not be explained by secondary causes. These elderly patients with primary pulmonary hypertension had symptoms common to younger patients with this disease, including dyspnea (eight patients), chest pain (five), pedal edema (four), and fatigue (one). In all but one patient, the initial diagnosis was incorrect, and the patients were thought to have more common diseases of the elderly that cause similar symptoms. Coexisting medical problems were common and further obscured the correct diagnosis. Survival was significantly shorter in those patients with symptoms of less than 6 months' duration. Primary pulmonary hypertension should be considered in the differential diagnosis in elderly patients with unexplained dyspnea and chest pain.