45 patients with gastrointestinal stromal tumors (GIST) were under observation. In 30 cases the GIST came from the stomach, in 8 cases - from the duodenum, and in 7 cases - from the small intestine. In all cases the diagnosis was confirmed by immunohistochemical study. Specific clinical manifestations of GIST were absent. Ultrasound detected the tumors that were more than 30 mm in diameter. The most informative diagnostic technique was computerized tomography with a contrast. All patients were operated. 29 patients with a diameter of tumor more than 50 mm had traditional open operation. In case the tumor oversteped the limits of the capsule or capsule's damage during the operation, the extirpation of the gastrocolic omentum was done. If the GIST were less than 50 mm they were extracted with the robot-assisted or laparoscopic methods. The long-term results of the treatment (from 3 to 60 months) of 28 patients were analyzed. 3 patients died of disease progression, 1 patient had metastasis in liver and 24 patients hadn't the signs of relapse.