 Even with this information, there are no standards of VTE prophylaxis in obese patients. Optimal means of delivering safe and effective thromboprophylaxis in this group is unknown. When using LMWHs, consensus recommendations have been to monitor peak anti-Xa activity targeting a level of 0.1-0.2 unitsmL. 5 However, many hospitals do not have access to anti-Xa monitoring. Studies evaluating the predictability of weight-based prophylactic dosing of tinzaparin have demonstrated that anti-Xa levels are predictably achieved and therefore, laboratory monitoring may not be necessary with this dosing strategy.7 However, tinzaparin is not widely utilized in the U.S. and uncertainties remain about whether predictable anti-Xa levels can be achieved with a weight-based prophylactic regimen using the more commonly used drug enoxaparin. If weight-based dosing with enoxaparin is shown to result in predictable anti-Xa activity in obese patients, the need for monitoring would be obviated. 