BACKGROUND: The bariatric surgical population is a particularly high risk population for VTE. It is unclear if standard (i.e. non-adjusted) thromboprophylaxis doses of low-molecular weight or unfractionated heparin provide adequate protection for obese patients undergoing bariatric surgery, or if higher doses are required. We sought to determine whether a weight based thromboprophylactic dosing regimen is safe and effective in the post-operative period for obese patients undergoing bariatric surgery. METHODS: A systematic literature search strategy was conducted using MEDLINE, EMBASE, the Cochrane Register of Controlled Trials and all EBM Reviews. Pooled proportions for the different outcomes were calculated. RESULTS: A total of 6 studies (1 RCT, 4 cohort studies and one quasi experimental trial) containing 1,858 patients were include in the systematic review. Post bariatric surgery patients receiving weight-adjusted prophylactic doses of heparin products, had an in hospital rate of VTE of 0.54% (95% CI: 0.2 to 1.0%) compared to 2.0% (95% CI: 0.1 to 6.4%) for those that did not weight adjust doses. Rates of major bleeding were similar for both groups: 1.6% (95% CI: 0.6 to 3.0%) for patients receiving weight-adjusted dosing compared to 2.3% (95% CI: 1.1% to 3.9%) for those receiving standard doses of heparin products. CONCLUSIONS: Adjusting the dose of heparin products for thromboprophylaxis post-bariatric surgery seems to be associated with a lower rate of in hospital VTE compared to a strategy of not adjusting the dose, although this did not reach statistical significance. This practice does not lead to an increase in adverse major bleeding events.