Recent studies have shown that lymphopenia with cytokine storm syndrome is frequentlyfound in COVID-19 patients. These features may suggest that the modified immune systemplays a key role in determining disease progression. Lymphopenia or lymphocytopenia is acondition in which the number of lymphocytes in the blood is low. Although T cells can beincreased at the onset of COVID-19, these patients tend to have low lymphocyte counts,which is associated with increased COVID-19 severity. Thus, individuals who died ofCOVID-19 have been shown to have significantly lower lymphocyte levels than survivors.There is evidence that myeloid cells play a role in the pathophysiology of coronavirusinfection, either directly as virus targets or indirectly as effectors of cytokinerelease syndrome. Monocytes are innate hematopoietic cells that maintain vascularhomeostasis and provide early responses to pathogens during acute infections. The role ofmonocytes and macrophages in the resolution of inflammation has also been emphasized asan important component of the response to SARS-CoV-2. Accordingly, it was investigatedwhether the change observed in blood monocyte levels was an effective parameter in theprognosis process in Covid-19 cases with lymphopenia, considering that monocyte levelscould be useful as a guide in the course of the disease.