Study aim: This study aims to investigate the effect of recombinant erythropoietin on the recovery process of COVID-19 patients. Design: concealed, randomized, single blinded, phase 2 controlled clinical trial with two arm parallel group design of 20 patients, using the placebo in the control group. Settings and conduct: This study will be performed at Shahid Mohammadi Hospital in Bandar Abbas. Patients enter the study after obtaining written consent, but will not know which group they belong to. Participants/Inclusion and exclusion criteria: All positive COVID-19 patients who have Hb≤9 and at least one of the severe COVID-19 symptoms and are willing to cooperate in this project will be included in the study. Patients with a history of coronary heart disease, thrombosis, deep vein thrombosis, chronic lung disease, diabetes mellitus, weakened immune system, end stage renal disease, liver disease, and patients with a history of taking oral contraceptive pills, systolic blood pressure more than 160 mm Hg, diastolic blood pressure more than 90 mm Hg and age over 65 and erythropoietin above 500 are excluded. Intervention groups: Patients are divided into two groups. In group A, the standard treatment for COVID-19 patients with recombinant erythropoietin is prescribed. In group B, patients receive standard COVID-19 treatment with the placebo. Main outcome variables: Patient clinical symptoms, Laboratory examinations of patients and Hemoglobin