Background: Psoriasis is a chronic, recurrent, immune-mediated inflammatory disease that affects 2%–3% of the world's population. It is related to genetic vulnerability, autoimmunity, mental health, and environmental factors. Pathogenesis is highly linked to abnormal interactions between innate immunity, T lymphocytes, and keratinocytes. Maresin 1 (Mar1) is one of the EPA-derived metabolites with substantial anti-inflammatory actions in inflammatory diseases. Objective: To investigate the possible association between serum level of Mer1 and psoriasis with variable degrees of severity and compare it with healthy subjects. Patients and Methods: We conducted a case-control study involving 60 psoriasis patients and 30 apparently healthy individuals of the same age and gender as controls. All participants were recruited from the Outpatient Clinic of the Department of Dermatology and Andrology at Benha University Hospitals. Comprehensive assessments, including history taking, general examination, and skin evaluation, were performed on all participants. Disease severity was determined using the Psoriatic Area and Severity Index (PASI). Serum samples were collected, and Mar1 levels were measured using an ELISA technique. Results: Mar1 level was considerably lower (p = 0.007) in cases compared to controls. At cut-off point of 26.9 pg/ml achieved 96% sensitivity and 93.5% specificity. Mar1 showed a significant negative correlation with disease duration and PASI score. Serum Mar1 significantly predicted the degree of disease severity. Conclusions: Serum Mar1 significantly decreased in psoriatic patients than controls. It could be valuable for possible diagnostic role and predicting disease pathogenesis, activity and severity of cases with psoriasis