This work deals with the investigation of the HLA system antigen, classes A, B, CW and DR, in 100 patients with dilated cardiomyopathy and 200 healthy donors. It was shown that the HLA system antigen is involved in the hereditary predisposition to dilated cardiomyopathy and in its clinical polymorphism determination. The HLA system antigen distribution in patients with dilated cardiomyopathy clearly differs from the same index in the general population following this medical examination. The direct connection between the dilated cardiomyopathy and the HLA DQA1 gene confirms the hypothesis on the genetic determinism of this disease.