Background: Venous thromboembolism (VTE) is a common postoperative complication after bariatric surgery with high mortality. Our study aimed to spotlight on the importance of anticoagulants after sleeve gastrectomy and its effect on lower limb deep venous thrombosis (DVT) incidence in obese patients with low BMI. Patients and methods: A prospective observational study was performed, including 200 patients with BMI between 35 and 45 kg/m2 undergoing laparoscopic sleeve gastrectomy (LSG) in the period between February 2017 and September 2018. Half of the patients received anti-thromboembolic dosage scheme of 0.5mg/kg/day with the induction of anaesthesia and for one week postoperatively (Group A) while the other half had no anticoagulation therapy (Group B). Results:Patients  were  followed  with  lower  limb  venous  duplex  at  2  weeks,  3  and  6  months  interval  from the operation or on appearance of symptoms of DVT. No patients had DVT in both groups by venous duplex. Conclusion: The incidence of lower limb DVT after LSG in patients with low BMI is not affected only by anticoagulants. We need further investigations including coagulation profile and congenital anticoagulation abnormalities to give an accurate idea about the influence of LSG on the incidence of DVT.