INTRODUCTION: The physical inactivity, hypoventilation, as well as chronic inflammation in obese patients aggravates their condition in various diseases. These features have become important with the advent of the COVID-19 pandemic, in which inflammation and platelet-activated coagulopathy are closely linked. AIM: To study laboratory parameters of inflammation and platelet apoptosis in obese patients using various types of anticoagulant prophylaxis of venous thromboembolic complications with the underlying COVID-19. MATERIALS AND METHODS: The study included 370 patients with COVID-19. Depending on the presence or absence of obesity and the type of parenteral anticoagulant, patients in our study were divided into groups: group 1 — non-obese + low molecular weight heparin (LMWH) (n = 114), group 2 — non-obese + unfractionated heparin (UFH) (n = 58), group 3 — obesity + LMWH (n = 76), group 4 — obesity + UFH (n = 66). The incidence of venous thromboembolic complications (VTEC), bleeding, general markers of the acute phase of inflammation, and specific markers of platelet apoptosis (phosphatidylserine and calreticulin) have been analyzed. RESULTS: At the end of hospital treatment, a decrease in ferritin levels was noted in patients both with and without obesity receiving LMWH. The concentration of calreticulin was higher in patients taking LMWH (groups 1 and 3). Phosphatidylserine levels were high in patients receiving LMWH only if they were obese. In patients taking UFH compared to LMWH, a high incidence of pulmonary embolism (PE) without a source (13.6% of cases versus 2.6%, respectively, p = 0.029) and PE with a source in the lower extremities (9.1% of cases versus 0%, respectively, p = 0.018) was found. When using LMWH, a lower incidence of bleeding was observed compared to using UFH (5.3% of cases versus 16.7%, respectively, p = 0.056). CONCLUSION: The levels of phosphatidylserine and calreticulin are higher in obese patients receiving LMWH. At the same time, patients in this group have a low incidence of VTEC and hemorrhagic complications compared to the group of patients taking UFH.