Aim: to analyze the results of a modified monoanastomotic gastric bypass technique in patients with morbid obesity. Materials and methods. The results of 30 morbidly obese patients who underwent gastric bypass surgery were studied. The patients were divided into two groups. Modified in our clinic laparoscopic monoanastomotic gastric bypass was performed in 19 patients (the main group). The control group included 11 patients after standard Roux-en-Y laparoscopic gastric bypass technique. Inclusion criteria were: patients of both sexes aged 18–60 years old with morbid obesity and body mass index (BMI) of 40 kg/m2 or more, and 35 kg/m2 or more in case of additional comorbidities (type 2 diabetes mellitus, hypertension, dyslipidemia, sleep apnea syndrome). Statistics were performed using the Statistica 13.0 software package by parametric and nonparametric statistical methods. Results. The postoperative period was 5 (4; 6) days in the main group and 7 (5; 8) days in the control group (P = 0.13). In both groups, the decrease in body weight ranged from 12 to 52 kg in 6 months. In the main group, the average weight loss was 29 kg in 6-month and 38 kg in 12-month period. BMI in 6 months was 31.28 kg/m2, in 12 months – 27.70 kg/m2. In the control group, this indicator was 27 kg/m2 and 44 kg/m2 in 6 months and 12 months, respectively. The average BMI in 6 months was 31.64 kg/m2, in 12 months – 26.03 kg/m2, respectively. Conclusions. Monoanastomotic gastric bypass in the modification by the clinic is an effective and safe operation for morbid obesity patients that can effectively and systematically reduce body weight. Monoanastomotic gastric bypass in modification by the clinic has the same strengths as the Roux-en-Y technique but avoids the risks associated with the second anastomosis and pathological bile reflux into the esophagus. Further studies are needed to evaluate the long-term results after modified monoanastomotic gastric bypass technique.