[Pulmonary arterial hypertension is a rare disease, but it occurs more often in systemic autoimmune diseases, where it represents one of the most severe, life-threatening complications. Its development is due to an immunoregulatory disorder characteristic to systemic diseases, persistent inflammation and the subsequent endothelial dysfunction, the presence of pathogenic autoantibodies, smooth muscle cell dysfunction and complex angiogenetic disorder. As a consequence of endothelial cell dysfunction, the balance between regulatory factors of vasoconstriction and vasodilation is disrupted. Intimal hyperplasia, endothelial cell proliferation, media hypertrophy and local thrombus formation can be observed and one of the main pathomorphological characteristic features, plexiform lesion develops, leading to obliterative vasculopathy. A more severe form of the disease develops in systemic sclerosis, which is explained by the main pathophysiological elements of scleroderma, namely immunoregulatory disorder, vasculopathy and fibroblast dysfunction. It is not easy to monitor the disease in these cases, because the deterioration can be caused by many other factors as well. Therefore, beseides the usual examinations, biomarkers and screening methods have a significant role. Treatment is not simple either, since no wellapplicable algorithms are available. In many disorders (systemic lupus erythematosus, mixed connective tissue disease, rheumatoid arthritis), effective immunosuppressive therapy started in time is crucial, whereas in case of systemic sclerosis, the principles of therapy applied for the idiopathic form should be followed.]