Venous thromboembolism (VTE) is a common complication after acute ischemic stroke. When screened by 125I fibrinogen scanning or venography, the incidence of deep-vein thrombosis (DVT) in stroke patients is comparable with that seen in patients undergoing hip or knee replacement. Most stroke patients have multiple risk factors for VTE, like advanced age, low Barthel Index severity score or hemiplegia. As pulmonary embolism is a major cause of death after acute stroke, the prevention of this complication is of crucial importance. Prospective trials have shown that both unfractionated heparin (UFH) and low molecular weight heparin (LMWH) are effective in reducing DVT and pulmonary embolism in stroke patients. Current guidelines recommend the use of these agents in stroke patients with risk factors for VTE. Some clinicians are concerned that the rate of intracranial bleeding associated with thromboprophylaxis may outweigh the benefit of prevention of VTE. Low-dose LMWH and UFH seem, however, safe in stroke patients. Higher doses clearly increase the risk of cerebral bleeding and should be avoided for prophylactic use. Both aspirin and mechanical prophylaxis are suboptimal to prevent VTE. Graduated compression stockings should be reserved to patients with a clear contraindication to antithrombotic agents.