Severely obese patients undergoing bariatric surgery (BS) are at increased risk for venous thromboembolism (VTE). How standard LMWH regimen should be adapted to provide both sufficient efficacy and safety in this setting is unclear. The aim of this study is to compare the influence of four BSD on peak anti-Xa levels in BS obese patients receiving high LMWH fixed doses to identify which one had the greatest impact and could further be proposed in LMWH-based thromboprophylaxis dosing algorithms.