DISCUSSION: Rivaroxaban is non-inferior to traditional anticoagulation in treatment of VTE. It has obvious advantages including its onset of action with half-life of 5-9 hours in healthy young subjects and 11-13 hours in elderly subjects along with limited drug interactions and similar risk of bleeding when compared to enoxaparin/Warfarin. Rivaroxaban was also reported to be better than placebo for preventing recurrence of VTE in the ‘Continued Treatment Study'. While rapid onset of action and lack of monitoring makes this drug an attractive alternative, these may also be its potential disadvantage. The lowest effective daily dose for rivaroxaban in the treatment of VTE was determined as 20 mg daily, although twice a day regimen was recommended to provide better clot resolution during the initial 3 weeks of therapy when risk of recurrence is highest. We report a case of recurrence of VTE within 10 days of therapy while the patient was on twice a day regimen and reported strict adherence. Although our patient was morbidly obese with a BMI of 45, no dose adjustment for obese patients has been recommended thus far. The lack of monitoring makes determination of the efficacy of anticoagulation with rivaroxaban unreliable and our report highlights first such case to be reported.