OBJECTIVE: The objective of this study was to evaluate the relationship between disease severity and biochemical parameters such as pentraxin3, CRP, fetuin-A, insulin and HOMA-IR levels in patients with psoriasis. PATIENTS AND METHODS: This study included 58 patients with psoriasis and 30 healthy controls admitted to Ankara Numune Teaching and Research Hospital between January 2011- August 2012. Serum pentraxin3, CRP, fetuin-A and insulin concentrations were determined. Also, HOMA-IR values were calculated. RESULTS: The serum values for CRP, insulin, HOMA-IR, pentraxin-3 and fetuin-A in patients with psoriasis were elevated than control subjects (p values = 0.002, 0.003, 0.003, 0.006 vs 0.007, respectively). According to the PASI score, patients were divided into three groups, minimal, moderate and severe psoriasis. There were positive correlation between the levels of CRP and insulin, HOMA-IR, PASI score. In addition, PASI score values were positively correlated with insulin, HOMA-IR and fetuin-A levels. CONCLUSIONS: Elevated levels of pentraxin3, CRP, fetuin-A, insulin and HOMA-IR might play a role in the pathogenesis of psoriasis. Higher CRP, fetuin-A, insulin and HOMA-IR concentrations were associated with the severity of the psoriasis.