Background: Chronic plaque psoriasis (CPP) is the most prevalent subtype of psoriasis, which is a chronic inflammatory disorder. MicroRNAs (miRNAs) may contribute to psoriasis pathogenesis through regulation of cytokine production. The pro-inflammatory cytokine, tumor necrosis factor-α (TNF-α), exerts a central role in psoriasis pathogenesis. Objective: to compare serum levels of miR-221-3p and TNF-α among CPP patients and healthy individuals. Methodology: 45 CPP patients and 45 healthy participants were included. The Psoriasis Area and Severity Index (PASI) score was utilized to assess the disease severity. Quantitative real-time PCR and ELISA techniques were used for assessment of serum concentrations of miRNA-221-3p and TNF-α, respectively. Results: Psoriatic patients showed significantly higher serum concentrations of miR-221-3p and TNF-α than healthy controls (P < 0.001). Moreover, a significant direct correlation was detected between serum miR-221-3p and TNF-α concentrations, on one hand, and both PASI score and disease duration (P < 0.001). Furthermore, a significant direct correlation was detected between concentrations of miR-221-3p relative expression and TNF-α in the sera of psoriatic cases (r = 0.876, P < 0.001). Conclusion: The miR-221-3p/TNF-α interaction may contribute to psoriasis pathogenesis. Moreover, miR-221-3p could be utilized as a biomarker to diagnose psoriasis and to assess its severity