Background and Design: Psoriasis is a chronic, inflammatory disease, and several biochemical markers play role in its inflammatory process. This study measured the levels of interleukin-12 (IL-12), IL-17a, IL-22 and IL-23, high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-α) and serum growth differentiation factor-15 (GDF-15) and aimed to detect the relationship of serum GDF-15 level with inflammation and disease severity. Materials and Methods: This study included 50 consecutive patients diagnosed with plaque-type psoriasis. For all patients, dermatological examinations were performed, and psoriasis area severity index (PASI) scores were recorded. Patients with PASI 20 severe (group 3) psoriasis. Results: No difference was observed between the patient and the control groups in terms of age, sex, IL-17a and IL-22. A statistically nonsignificant difference was detected in terms of IL-12 and IL-23. However, there was significant difference between two groups in terms of hs-CRP, TNF-α and GDF-15. GDF-15 was significantly different in all three groups (p1498.5 pg/mL (area under the curve: 0.813, p