To investigate the correlation of HLA-DMA and DMB alleles to some rheumatic diseases, HLA-DMA and DMB genes were detected in 11 patients with juvenile rheumatoid arthritis (JRA), 22 patients with psoriatic arthritis, 26 patients with Behcet's disease, 62 patients with ankylosing spondylitis (AS), and 138 unrelated healthy controls. There was no significant difference in phenotypic frequencies of HLA-DMA and DMB alleles between controls and patients with these rheumatic diseases. HLA-DMA and DMB genes are not related to the susceptibility of JRA, psoriatic arthritis, Behcet's disease, and AS.