Obese patients are at high risk for thromboembolic events during laparoscopic surgery. There have been no investigations of the impaired hemostatic system, by using different coagulologic tests and by evaluating the efficiency of their correction during gynecologic laparoscopic surgery in morbidly obese patients at this moment. Objective — to investigate blood coagulation parameters in order to determine whether thromboembolic events can be effectively prevented in morbidly obese and normal weight patients during laparoscopic hysterectomy. Subject and methods. Group 1 included 52 morbidly obese patients (body mass index — BMI, 48.82±8.0 kg/m2) with diseases of the uterus and its appendages; Group 2 comprised 30 normal weight patients (BMI, 23±1.9 kg/m2). Laparoscopic hysterectomy was carried out in 81 (98.8%) patients; laparoconversion was done in one patient with morbid obesity. In all the patients, the risk of thromboembolic events was assessed on the basis of an analysis of somatic diseases, the presence of cancer, age, and duration of surgical treatment. After surgery, there was anticoagulant therapy: subcutaneous nadroparin calcium 0.3 ml twice daily for 3 days, then with a switch over to anticoagulant tablets. Standard coagulologic tests and a thrombodynamic test were carried out to evaluate the hemostatic system. Results. In all the patients, morbid obesity was concurrent with severe extragenital diseases, mainly with hypertension, varicose vein disease, diabetes mellitus, and asthma; 38.4% of the patients with morbid obesity and 13.4% of those with normal weight were over the age of 60 years. Laparoscopic hysterectomy lasted more than 45 minutes in 92% of the patients with obesity and in 86.7% of those with normal weight. Every 2 patients with morbid obesity were diagnosed with malignant or pre-malignant processes in the uterine corpus and appendages after hysterectomy. The progression of hypercoagulation was intraoperatively recorded in both groups of patients. Evaluating the efficiency of the standard dose of low-molecular-weight heparin 0.3 ml (2850 IU anti-factor Xa activity) indicated the following: the patients with a BMI of less than 25 kg/m2 were recorded to have moderate hypocoagulation; those with morbid obesity (a BMI of less than 50 kg/m2) had normal coagulation; and the patients with a BMI of more than 55 kg/m2 had moderate hypercoagulaliton. Severe hypercoagulation was recorded in all the patients 12 hours after anticoagulation. Conclusion. There is evidence for a high risk for thromboembolic events when performing laparoscopic hysterectomy in patients with morbid obesity. It is appropriate to increase the single dose of nadroparin calcium, by taking into account BMI, and to administer the drug twice daily in morbidly obese patients.