Abstract: The results of pulmonary function tests in 40 patients with connective tissue disease were ana lysed, the main change found being decrease of lung volume, maximal voluntory ventilation and diftusion capacity, and hypoximia as well as dysfunction of small airway. From these results the authors concluded, that pulmonary function tests are useful for the diagnosis of connective tissue diseases, and some of these tests, such as DLCO measurement, may be helpful to discover the early respiratory impairment in connective tissue disease.