Severe pulmonary hypertension without pulmonary fibrosis occurred in 10 patients with the CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dysfunction, sclerodactyly, telangiectasia), reputedly a benign variant of progressive systemic sclerosis. Time from the initial symptom, Raynaud's phenomenon, to the recognition of pulmonary hypertension was as long as 40 years. Pulmonary hypertension and increased pulmonary vascular resistance was shown in all patients. Autopsy examination in three of six deaths attributable to pulmonary hypertension showed intimal proliferation with myxomatous change in the small- and medium-sized pulmonary arteries similar to changes in the digital arteries of patients with scleroderma and Raynaud's phenomenon, and interlobular renal arteries of those with "scleroderma kidney." It is concluded that the CREST syndrome is not entirely benign but may be complicated, after a long clinical course, by progressive pulmonary vascular obliteration, pulmonary hypertension, and death in the absence of significant pulmonary fibrosis.