Background. This prospective randomized study compares the incidence of silent deep venous thrombosis (DVT) among 2 groups of patients who underwent laparoscopic bariatric surgery. The first group received mechanical thromboprophylaxis only, while the second group received a combination of mechanical and chemical thromboprophylaxis. Methods. This study included 150 morbidly obese patients who underwent primary one-stage laparoscopic bariatric surgery (sleeve gastrectomy and mini-gastric bypass) over a 6-month period. Patients were randomly assigned to 2 groups: group A (n = 75) was subjected to mechanical thromboprophylaxis in the form of perioperative elastic stockings on both lower limbs and early postoperative ambulation, and group B (n = 75) was subjected to combined mechanical thromboprophylaxis and chemical thromboprophylaxis in the form of 40 mg subcutaneous enoxaparin 12 hours before surgery and postoperative enoxaparin (40 mg subcutaneous every 24 hours) for 2 weeks. Bilateral lower limb venous duplex was done for all patients before discharge, on the second and fourth weeks postoperatively, to detect silent DVT. Results. Nine patients out of 150 patients developed silent DVT (6%). All patients among group A were subjected to mechanical thromboprophylaxis only (12%) [P = .247, relative risk: .45, 95% confidence interval; .37-.62]. There was no silent DVT among group B who received combined mechanical and chemical thromboprophylaxis. No bleeding complications were reported in both groups. Conclusion. Combined mechanical and mechanical thromboprophylaxis is effective and safe in the prevention of silent DVT after laparoscopic bariatric surgery. Trial registration: The trial was registered in the Thai Clinical Trials Registry (TCTR20200127002) on January 20, 2020 retrospectively.