Psoriasis (PS) is a common hyperproliferative and chronic inflammatory disease of the skin, which involves both genetic and environmental factors. The A disintegrin and metalloproteinase 33 (ADAM33) gene, located on chromosome 20p13, has recently been identified as an asthma-susceptibility gene by positional cloning. Recently, it has been reported that ADAM33 contributed to PS risk in the French population and white North Americans. To observe the relationship between ADAM33 gene and PS, a case-control study was conducted in a Han Chinese population. Three polymorphic sites (T1, T2, and V4) were genotyped using polymerase chain reaction-restriction fragment length polymorphism analysis in 106 patients with PS and 125 healthy controls. We observed a decreased frequency in the CG genotype and GG genotype of ADAM33 rs2787094 (V4) in cases compared with controls (p = 0.045, odds ratio = 0.461, 95% confidence interval = 0.215-0.992, and p = 0.044, odds ratio = 0.447, 95% confidence interval = 0.203-0.987, respectively). Our data suggest that the ADAM33 gene may be associated with PS risk in the Chinese population.