The mannose receptor (MR-CD206), is one of type I transmembrane proteins that possess structurally and functionally related domains as a pattern recognition receptor. It is expressed primarily on the membrane of M2 macrophages and dendritic cells, which have an important role in nonspecific and specific immunity. In this study, the serum levels of MR were examined in rheumatoid arthritis (RA). MR concentrations were measured in the sera of 50 patients and 38 healthy individuals (control) groups. COVID-19 infection in RA patients has also been investigated. The MR value of RA patients was significantly higher than that of the control group (p <0.005). There is no significant difference in gender, however males have higher MR levels than females, whereas COVID-19 infected RA patients did not show any change or significant difference in the concentrations of MR serum level. We found that untreated RA patients have elevated serum MR levels, making MR a potential marker of the pathogenesis and progression of RA.