Psoriasis (PS) is a common hyperproliferative and chronic inflammatory disease of the skin. It is influenced by both genetic and environmental factors. The ADAM33 (a disintegrin and metalloproteinase 33) gene located on chromosome 20p13, has recently been identified as an asthma-susceptibility gene by positional cloning. Recently, ADAM33 has been suspected to be associated with PS. To study the association between ADAM33 and PS in the northeastern Chinese population. A total of 240 PS patients and a control group of 237 healthy volunteers were recruited for this study. Five polymorphic loci (V4, T+1, T2, T1, S2) of ADAM33 were selected for genotyping. Genotypes were determined by using the polymerase chain reaction-restriction fragment length polymorphism method. We observed the frequency of the rs2787094 C allele was significantly higher in cases than in controls (50 vs. 33%, P < 0.0001).Similarly, the rs528557 C allele exhibited a significantly increased frequency in PS patients compared with healthy controls (35 vs. 21%, P < 0.0001). We also found that the frequencies of H3 (CGGAC), H6 (CGGGG) haplotypes were significantly higher in the case group than in the control group (P = 0.006, 0.028, respectively). In contrast, the haplotype H9 (GAAAG) was more common in the control group than in the case group (P = 0.018). Our data suggest that the ADAM33 polymorphisms may be associated with PS in the northeastern Chinese population.