A large number of trials have shown that many patients with venous thromboembolism can be treated as outpatients by using low molecular weight heparin. However, the amount of physical activity is neither mentioned in the study protocols nor in the instruction brochures, which are given to the patients. In most institutions, the fear of dislodging clots by ambulation is more common than the consideration of thrombus propagation and of recurrence; therefore, bed rest is recommended at least for the initial stage. There have been two randomized trials showing that bed rest as a part of the initial treatment of patients with deep vein thrombosis (DVT) is not able to substantially reduce the incidence of pulmonary emboli detected by repeat lung scanning. In one study performed in patients with proximal DVT, it could be demonstrated that leg compression and walking exercises are able to reduce edema and pain more rapidly and more effectively than bed rest. Progression of the thrombus size assessed by an independent Duplex examiner was statistically significantly greater in those patients confined to bed when compared with ambulatory patients with compression therapy. By counteracting against venous stasis, walking exercises and compression therapy have an important impact on the clinical outcome and should therefore be addressed in future studies. (C) 2002 Lippincott Williams Wilkins, Inc.