Severe COVID-19 is associated with venous thromboembolic events and and immuno-thrombotic phenomena, responsible for pulmonary vascular damage. This review summarizes the current knowledge on thrombotic risk in COVID-19 inpatients, the potential predictive factors (including D-dimer) and the randomized trials studying the effect of intermediate or therapeutic-dose anticoagulation on the clinical and thrombotic prognosis. Despite the initial hope, therapeutic anticoagulation does not improve the clinical prognosis in critically ill inpatients, and standard prophylactic anticoagulation is therefore recommended. In non-critical inpatients, the use of therapeutic anticoagulation may help reduce the risk of severe clinical deterioration, but its risk-benefit will be clarified in ongoing studies and meta-analyzes.