Psoriasis is recognized not only as a skin disease but also as a systemic disorder. Interleukin-31 (IL-31) may be associated with psoriasis and systemic inflammation. We aimed to quantify serum IL-31 levels in patients with psoriasis and explore their associations with specific clinical manifestations. Thirty patients with psoriasis and 30 healthy controls were included in this study. Demographic information and clinical characteristics were obtained through physical examination and medical history review. Serum IL-31 levels were measured using an enzyme-linked immunosorbent assay. IL-31 concentration was significantly higher in patients with psoriasis than those in the control group (p<0.001). Patients with psoriasis vulgaris, psoriasis erythroderma, and pustular psoriasis had significantly higher serum IL-31 levels than healthy controls. Additionally, serum IL-31 levels were associated with itch numerical rating scale (NRS) scores and body mass index (BMI) but not with disease severity as measured by the Psoriasis Area and Severity Index (PASI). In patients with psoriasis, increased serum IL-31 levels correlated with itch severity but not with PASI. This suggests that IL-31 may play a critical role in the pathogenesis of psoriasis and could be a valuable target for further studies and therapeutic interventions.