BACKGROUND: Thirty percent of Covid-19 patients admitted to intensive care units present with thrombotic complications despite thromboprophylaxis. Bed resting, obesity, hypoxia, coagulopathy, acute excessive inflammation are potential mechanisms reported by previous studies. Better understanding of the underlying mechanisms leading to thrombosis is crucial for developing more appropriate prophylaxis and treatment strategies. OBJECTIVE: We aimed to assess fibrinolytic activity and thrombin generation in 78 Covid-19 patients. PATIENTS AND METHODS: Forty eight patients admitted to intensive care unit (ICU) and 30 patients admitted to the internal medicine department were included in the study. All patients received thromboprophylaxis. We measured fibrinolytic parameters (tPA, PAI-1, TAFI, alpha2 anti-plasmin, and tPA-modified ROTEM), thrombin generation, and other coagulation tests (D-dimer, fibrinogen, FVIII, antithrombin). RESULTS AND CONCLUSIONS: We observed two key findings: a high thrombin generation capacity which remained within normal values despite heparin therapy and a hypofibrinolysis mainly associated with increased PAI-1 levels. A modified ROTEM (TEM-tPA) is able to detect both hypercoagulability and hypofibrinolysis simultaneously in Covid-19 patients with thrombosis.