Pulmonary haemodynamics at rest and during exercise was studied in 30 patients with histologically confirmed sarcoidosis. All subjects were divided into three groups according to the stage of the disease assessed by radiological image of pulmonary lesions. At rest, in stage I and II patients, the mean pulmonary pressure (PAP) was normal. In stage III patients, a slight pulmonary hypertension was found. During exercise, a rise in PAP in stage I and II subjects was within the normal limits for a given workload, although in individual stage II subjects a rise in PAP was abnormally high. In all stage III patients a rise in PAP was pathologically elevated.