Pulmonary hypertension is one of the complications in the pulmonary manifestation of SLE. Following a two year SLE history a patient developed pulmonary hypertension although his chest radiograph showed neither pulmonary changes nor signs of hypertension. In two other patients, interstitial fibrosis, pleurisy and pulmonary hypertension were the initial manifestations of SLE. They all complained of dyspnoea and respiratory chest pain. Lung function studies showed restrictive changes, reduced lung compliance and, by two patients, reduced diffusion capacity. Lung biopsy performed in one patient revealed interstitial fibrosis, focal lymphocyte infiltrations and intima proliferation of the arterioles. All three patients were treated with anticoagulants in addition to steroids and cytotoxic drugs. After a period of 8 to 42 months examinations were repeated and all three patients showed improved hypertension and less physical ailment. The radiographs from two patients even revealed an improvement of their pulmonary changes.