Background: COVID-19 is a highly infectious viral infection caused by SARS-CoV-2 that can affect persons of all ages, from infants to the elderly, resulting in various clinical presentations and a global pandemic that resulted in a significant loss of human life globally. Objective: The current study aims to measure IL-10 in serum of COVID-19 patients with different degrees of severity to identify its significance. Patients and methods: A case control study was carried out in Clinical Pathology Department and conducted on 30 COVID-19 patients (some were selected from isolation hospital and some were clinically stable outpatients with PCR-proven SARS-CoV-2 infection) and 20 normal subjects as reference. Serum IL10 was measured using Enzyme-linked immune-sorbent assay (ELISA) technique. Results: In comparison to control groups, COVID-19 patients with different degrees of severity had serum levels of IL-10 that were significantly higher. Also, urea, creatinine, CRP, D-dimer, ferritin and IL6 are significantly higher whereas Hb concentration, platelet count and lymphocyte percentage are much lower. In COVID-19 patients, IL-10 showed positive correlations with CRP, ferritin, D-dimer, and IL-6, but negative correlations with platelet count and lymphocyte percentage. Conclusions: The current study offers proof that severe and non-severe COVID-19 cases can be distinguished based on the outcomes of the laboratory tests conducted at the time of admission. Additionally, it implies that cytokines are crucial to COVID-19 pathogenesis. Furthermore, it demonstrates that serum IL-10 can be used to predict severity of COVID-19.