Twenty-four patients with connective tissue disease as defined by ARA criteria were submitted to a thorough cardiological and pulmonary diagnostic evaluation. Mean pulmonary arterial pressure was elevated in 54 per cent of the patients, a left-ventricular functional disorder taking the form of elevated pulmonary capillary occlusive pressure was almost equally as frequent. Interindividual comparisons suggest only a low progressivity of the cardiac involvement, while pulmonary involvement progresses rapidly, to become the prognostically predominating factor. This suspicion must be checked by performing follow-up examinations with repeated cath. examinations of the right heart in individual patients. In common with ACE determinations, haemodynamically effective pericardial disorders are of no significance in connective tissue diseases. Patients with "collagenosis" should be submitted to right-heart catheterisation early on. Attempts at therapy taking the form of aggressive treatment of the underlying disease or administration of nitrates or calcium antagonists, would appear meaningful.