Psoriasis vulgaris is a chronic skin disorder characterized by infiltration of inflammatory elements, keratinocyte hyperproliferation and altered differentiation. Although the pathogenesis of psoriasis is not fully understood, there is solid evidence of a susceptibility locus in the human leukocyte antigen (HLA) region. To investigate whether HLA-DQA1 and DQB1 alleles are associated with genetic susceptibility to psoriasis vulgaris in Chinese Han. The polymerase chain reaction-sequence-specific primer (PCR-SSP) method was used to analyse the distribution of HLA-DQA1 and DQB1 alleles in 189 patients with psoriasis and 273 healthy controls. The HLA-DQA1*0104 (OR = 2.33, P = 0.0001154, Pc = 2.0 x 10-3), DQA1*0201 (OR = 3.36, P < 1.0 x 10-7, Pc < 1.0 x 10-6), DQB1*0201 (OR = 1.64, P = 0.0192, Pc > 0.05) and DQB1*0303 (OR = 1.55, P = 0.0377, Pc > 0.05) alleles were more prevalent in patients with psoriasis vulgaris than in controls, and HLA-DQA1*0501 (OR = 0.30, P = 0.0000039, Pc < 4.0 x 10-5) alleles were less prevalent. The HLA-DQA1*0104 (OR = 2.42, P = 0.0001159, Pc < 2.0 x 10-3), DQA1*0201 (OR = 3.74, P < 1.0 x 10-7, Pc < 1.0 x 10-6) and DQA1*0501 (OR = 0.30, P = 0.0000374, Pc < 4.0 x 10-4) alleles were only associated with type I psoriasis. HLA-DQA1*0104 and DQA1*0201 were more prevalent in patients with or without a family history of psoriasis. However, the DQA1*0501 allele was only more prevalent in patients without a family history of psoriasis. HLA-DQA1*0104 and DQA1*0201 alleles may be psoriasis susceptibility genes or may be in close linkage with the susceptibility genes. The HLA-DQA1*0501 allele seems to have a protective effect against the development of psoriasis vulgaris in Chinese Han. There may be a difference in genetic background between psoriasis patients with and without a family history of psoriasis.