Increased prevalence of Venous thromboembolism (VTE), as defined by deep-vein thrombosis (DVT), central venous catheter (CVC) related thrombosis or pulmonary embolism (PE) in cancer patients has become a major therapeutic issue. Considering the epidemiology and each national recommendations on the treatment of VTE in cancer patients, we analysed guidelines implementation in clinical practice. Thrombosis is the second-leading cause of death in cancer patients and cancer is a major risk factor of VTE, due to activation of coagulation, use of long-term CVC, the thrombogenic effects of chemotherapy and anti-angiogenic drugs. Three pivotal trials (CANTHANOX, LITE and CLOT) and several meta-analysis led to recommend the long term (3 to 6 months) use of LMWH during for treating VTE in cancer patients with a high level of evidence. The Italian Association of Medical Oncology (AIOM), the National Comprehensive Cancer Network (NCCN), the American Society of Clinical Oncology (ASCO), the French "Institut National du Cancer" (INCa), the European Society of Medical Oncology (ESMO) and the American College of Chest Physicians (ACCCP) have published specific guidelines for health care providers regarding the prevention and treatment of cancer-associated VTE. Critical appraisal of these guidelines, difficulties in implementation of prophylaxis regimen, tolerance and cost effectiveness of long term use of LMWH may account for large heterogenity in daily clinical practice. Homogenization of these guidelines in international consensus using an adapted independent methodological approach followed by educational and active implementation strategies at each national level would be very valuable to improve the care of VTE in cancer patients.