Psoriasis can be described as a T-cell-mediated disease, with a complex role for variety of cytokines and other factors. Among the inflammatory molecules influencing the keratinocites, TNF-α appears critical in sustaining most of the clinical manifestations of psoriasis. It is postulated that changes in cytokine production both locally and systemically could be useful in monitoring disease activity. The aim of the study was to evaluate serum levels of tumor necrosis factor alpha (TNF-α) in patients with psoriasis and the healthy subjects, and also to assess a possible association between TNF-α, clinical type and severity of disease. We studied the levels of serum TNF-α in 60 patients with psoriasis and in the serum of helthy 20 controls. According to the clinical type of disease, patients with psoriasis were divided into four groups: chronic plaque psoriasis (CPP), erythrodermic psoriasis (EP), pustular psoriasis (PP) and psoriatic arthritis (PA). Blood samples were collected from all psoriasis patients and from healthy control subjects. Serum level of TNF-α were measured by an enzyme-linked immunosorbent assay (ELISA) technique. The severity of CPP was assessed by Psoriasis Area and Severity Index (PASI). Serum levels of TNF-α in patients with psoriasis were significialy higher than in the control group (3.25+1.74 pg/mL vs 0.20+0.01pg/mL, respectively). Significantly elevated serum TNF-α was in patients with PP type (7.39+6.92 pg/mL). There was statistically significant difference between the mean level of TNF-ɑ compared to the clinical type of psoriasis (p<0.05). The mean PASI score in patients with CPP was 0.56±12.45. It was not found statistically significant correlation between serum level of TNF-ɑ and PASI score in patients with CPP (p>0,05). Our results have demonstrated the imortance of determining serum levels of TNF-ɑ in patients with psoriasis. Further investigations are required to clarify the pathogenic role and clinical significance of TNF-ɑ, and these findings may provide important clues to assist in the development of new therapeutic strategies for patients with psoriasis.