To probe into the genetic background and immunopathogenesis of dilated cardiomyopathy (DCM), HLA-DRB1 gene polymorphism in 68 patients with DCM and 175 normal control subjects were analyzed by using the polymerase chain reaction/sequence specific primer (PCR/SSP) techniques. It was found that the frequencies of HLA-DRB1* 15 and HLA-DRB1* 03 alleles were significantly lower in DCM patients than those in normal controls (14.71% vs 29.71% and 4.41% vs 15.43%, respectively), the relative risks (RR) in the DCM patients being 0.41 and 0.25, respectively, all P < 0.05. However, the frequencies of HLA-DRB1* 11 and HLA-DRB1* 12 alleles were significantly higher in the DCM patients than in controls (29.4% vs 12.00% and 36.76% vs 12.57%, respectively) with the RR in the DCM patients being 3.06 and 4.04, respectively, all P < 0.01. These findings further demonstrated that immunogenetics might play a predominant pathogenetic role in partial DCM patients.