© Copyright 2022, Mary Ann Liebert, Inc., publishers 2022.Objectives: The aim of the study was to investigate the effects of bemiparin administration for 15 and 30 days on deep vein thrombosis (DVT) in high-fat diet-induced rats, followed by sleeve gastrectomy (SG) for DVT prophylaxis. Setting: The study was conducted at the Kobay Experimental Animals Laboratory. Materials and Methods: Forty rats were fed a high-fat diet to induce obesity. They were then equally divided into four groups (n = 10); group 1 (control group); group 2 (nonbemiparin group); and group 3 (15-day bemiparin group) and group 4 (30-day bemiparin group) in which bemiparin therapeutic doses were administered for 15 and 30 days, respectively. Sixteen weeks after feeding, SG was performed on rats from groups 2, 3, and 4. Doppler ultrasonography was performed to investigate thrombosis of the inferior vena cava and iliac veins in all rats before and 1 month after SG. Rat vena cava, iliac veins, and lung tissues were removed to determine venous thrombosis status and investigate microthrombi through histological examination. Results: No statistically significant difference was found between groups in terms of the thickness of intima-media (μm), thrombus area (μm2), and erythrocyte, leukocyte, and platelet/fibrin values of the iliac veins (p > 0.05). A statistically significant difference was found between groups in terms of the presence of thrombus and radiological status of the vena cava (p < 0.05). In addition, the measurement percentage was found to be 100% in group 2, 37.5% in group 3, and 12.5% in group 4. Conclusion: We believe that administration of bemiparin once a day for 30 days can be a safe and effective treatment method in the prevention of microthrombi, following SG.