Introduction. Platelets play an important role in arterial thrombosis, and the effects of SARS-CoV-2 on platelets contribute to an increased risk of thrombosis.Aim. To evaluate platelet link of hemostasis system and polymorbidity in patients with acute coronary syndrome and COVID-19 at the time of admission to the hospital.Materials and methods. The case-control study included 96 pairs of patients with acute coronary syndrome (ACS). The groups were adjusted by gender, age and diagnosis of ACS. Group 1 had ACS and COVID-19, Group 2 had ACS without COVID-19. Blood indicators were examined using the Mindray BC-5150 and ABX Micros-60 automatic hematology analyzers, the results of which were comparable Statistica 13.0 environment was used for statistical processing. The study was approved by the Local Ethics Committee of Ural State Medical University by Protocol No. 9 dated 10.22.2021.Results. Platelet level (PLT) was 242 (178÷299) x 109/L Group 1 and 236 (199÷291) x 109/L, in Group 2, p = 0.927. Mean platelet volume (MPV) was 10.0 (9.3÷11.5) fl in Group 1 and 8.0 (7.6÷8.8) fl, in Group 2, p < 0.001. Platelet distribution width (PDW) was 16.2 (15.9÷16.4) in Group 1, and 15.7 (14.7÷16.7) in Group 2, p < 0.001. Plateletcrit (PCT) was 0.24 (0.18÷0.30)% in Group 1 and 0.19 (0.16÷0.24)% in Group 2, p < 0.001. Platelet-to-lymphocyte ratio (PLR) 159.4 (109.5÷232.9) in Group 1 and 118.4 (88.2÷158.1) in Group 2, p < 0.001. The Charlson polymorbidity index in Group 1 was 5 (4÷6) points, in Group 2 – 4 (4÷6) points, p = 0.047.Conclusions. Higher PDW, MPV, PCT values with the same PLT, higher PLR level and higher polymorbidity at the time of hospitalization may indicate more pronounced platelet activation due to inflammation, severe immunosuppression and concomitant diseases in patients with COVID-19.