BACKGROUND/AIM: SARS-CoV-2 enters the cell through the binding of the S glycoprotein on the surface of the virus to the angiotensin-converting enzyme 2 (ACE-2) in the host cells and also SARS-CoV S protein binding to ACE-2 was inhibited by anti-A antibodies. The aim of the study was to investigate the relationship between blood groups and the course of COVID-19 in
Turkey. MATERIALS AND METHODS Laboratory confirmed COVID-19 patients aged 18 and over (n=39.850) were randomized in age and gender-matched groups according to blood groups Results: Advanced age, male gender and blood group A were found to be related with increased rate of intensive care unit (ICU) admission (OR =1.089, 95% CI: 1.085-1.093 for age; OR=1.963, 95% CI: 1.737-2.218 for male gender; OR=1.216, 95% CI: 1.023-1.446 for blood group A). When blood group O individuals were compared to non-O individuals, no significant difference was observed regarding the rate of hospital and ICU admission, mechanical ventilation (MV) support, length of hospital and ICU stay, and case fatality rate (CFR). The CFR in patients with blood group A, B, O, and AB were 2.6%, 2.2%, 3.1%, and 2.3%, respectively. There were no significant differences between Rh-negative and positive patients regarding the rate of hospital and ICU admission (p=0.280 and p=0.741, respectively), also the rate of MV support and CFR was similar (p=0.933 and p= 0.417). CONCLUSION Our study revealed that ABO and Rh blood groups do not have any impact on the rate of hospital admission, hospital and ICU stay, MV support, and CFR.