Background: Venous thromboembolism (VTE) is a major health care problem resulting in significant mortality, morbidity and increase in medical expenses. Patients with malignant diseases represent a high risk population for VTE. The American College of Chest Physicians (ACCP) proposed, since 1986, prophylaxis guidelines that are unequally respected in surgical practice., Methods: DIONYS is a multinational, longitudinal and non-interventional registry including patients having undergone abdominal or pelvic surgery for cancer in Latin America, Africa and the Middle East. Patients were evaluated with regard to VTE prophylaxis, during three consecutive visits, for their adherence to ACCP 2008 guidelines. Data were collected on type and duration of VTE prophylaxis, adherence to guidelines, and compliance with prescriptions, complications and possible reasons for omission of prophylaxis., Results: Between 2011 and June 2012, 921 adult patients were included and divided into abdominal (435), pelvic (390) and combined abdominal and pelvic surgery (96), 65.4 % being females. VTE prophylaxis was prescribed to 90 % of patients during hospitalization and to 28.3 % after hospital discharge. Prescriptions adhered to ACCP guidelines in 73.9 % of patients during hospitalization and 18.9 % after discharge. The reason of non-adherence was mainly the clinical judgment by the physician that the patient did not need a prophylaxis. The most commonly prescribed type of prophylaxis was pharmacological (low molecular weight heparin)., Conclusion: A wide gap exists between VTE prophylaxis in daily practice and the ACCP 2008 guidelines, in abdominal and pelvic cancer surgery. A better awareness of surgeons is probably the best guarantee for improvement of VTE prophylaxis in surgical wards.