Background and Design: Psoriasis is a T cell-mediated autoimmune skin disease characterized by hyperproliferation of keratinocytes and accumulation of activated T cells responding to a hitherto unidentified antigenic stimulus. Tumor necrosis factor-alpha (TNF-alpha) plays an essential role in the induction and maintenance of psoriatic lesion. Neopterin is a non-specific immunological marker of cellular immune activation, which is produced by human monocytes/macrophages as a result of interferon-gamma secretion by activated T lymphocytes. The aim of the presented study was to determine the levels of serum neopterin and TNF-alpha in psoriatic patients and to evaluate whether Psoriasis Area correlated with Severity Index (PASI) and serum levels of neopterin and TNF-alpha.