Genes encoded within the MHC complex on chromosome 6 are thought to play an important role in the pathogenesis of psoriasis. A potential candidate is tumor necrosis factor alpha (TNF-alpha) gene. Psoriasis features an increased activity of the proinflammatory cytokine TNF-alpha in affected lesions. TNF-alpha promoter region contains several polymorphisms, including G/A transition at position -308, which influences transcriptional activity of TNF-alpha. This study was performed to investigate the association between TNF-alpha single nucleotide polymorphism and susceptibility for psoriasis vulgaris.DNA from 78 patients with psoriasis vulgaris and 74 healthy volunteers with no personal and family history of psoriasis was investigated. TNF-alpha promoter gene single nucleotide polymorphism (SNP) in position 308 was evaluated by PCR-SSP. The results were compared between group of psoriatic patients, divided into early onset of psoriasis (type I) and late onset of psoriasis (type II) subgroups, and healthy subjects.There were no significant differences in the polymorphism of TNF-alpha promoter -308 (genotype distribution, allele frequencies) between psoriasis patients and healthy controls. Similar results were obtained analyzing subgroups of psoriasis patients (type I and type II of psoriasis) and gender groups.TNF-alpha promoter single nucleotide polymorphism (-308) is not associated with susceptibility to psoriasis vulgaris.