Neurosurgical patients are at great risk for venous thromboembolism. Thromboprophylaxis is either with unfractionated heparin or low molecular weight heparin (LMWH). In neurosurgery, this is a matter of debate because of fear from bleeding. Few randomized studies show that chemical prophylaxis is safe after elective neurosurgeries. Prophylaxis with gradual elastic stocking and venous pump may be affective but there are not enough studies and trials examining their efficacy. Larger trials are needed to examine the safety of unfractionated heparin versus LMWH in neurosurgical patients including head injury patients.