A systematic literature search was performed and patients were selected as obese patients undergoing bariatric surgery or obese patients undergoing nonbariatric surgical procedures. In addition, patients were stratified according to low risk of venous thromboembolism and high risk of venous thromboembolism (age >55 years, BMI >55 kg m−2, history of venous thromboembolism, venous disease, sleep apnoea, hypercoagulability or pulmonary hypertension). Prophylaxis of venous thromboembolism was analysed depending on the type of modality: compression devices of the lower extremities (including intermittent pneumatic compression and graduated compression stockings), pharmacological prophylaxis or inferior vena cava filters. Two prospective studies compared mechanical devices and pharmacological prophylaxis vs. a mechanical device alone without significant differences. A few randomised controlled studies and most of the prospective nonrandomised studies showed that low-dose low molecular weight heparin (3000 to 4000 anti-Xa IU 12 h−1 subcutaneously) was acceptable for obese patients with a lower risk of venous thromboembolism, but a higher dose of low molecular weight heparin (4000 to 6000 anti-Xa IU 12 h−1 subcutaneously) should be proposed for obese patients with a higher risk of venous thromboembolism. Extended prophylaxis for 10 to 15 days was well tolerated for obese patients with a high risk of venous thromboembolism in the postdischarge period. The safety and efficacy of inferior vena cava filters in bariatric surgical patients is highly heterogeneous. There were no randomised trials that analysed prophylaxis of venous thromboembolism in obese patients undergoing nonbariatric surgery. Higher doses of anticoagulants could be proposed for obese patients with a BMI more than 40 kg m−2. The lack of good quality randomised trials with a low risk of bias did not allow us to propose strong recommendations.