The question of when and how intensively patients with deep-venous thrombosis (DVT) can ambulate remains scarcely underlined. The authors evaluated the evolution of DVT by comparing bed rest and mobilization and using all variables potentially relevant to a risk/benefit evaluation in 252 patients. The end points were the progression of the thrombotic disease and the incidence of pulmonary embolism (PE) at 30 days. Immobilized patients had a higher incidence of events (hazard ratio 4.39; P < .0001). At multivariate analysis, immobilization (hazard ratio 2.41; P = .026) and the lack of leg compression (hazard ratio 4.58; P = .009) were the only independent predictors of the clinical end point. This retrospective analysis raises the question as to whether all patients with confirmed DVT should ambulate and receive an adequate leg compression. A prospective study is needed to determine whether immobilization of such patients actually increases their risk of developing pulmonary embolism.