Gastric cancer continues to occupy the leading positions in terms of morbidity and mortality among malignant tumors. Surgical treatment remains the main method of treatment within the combined approach. However, now the level of postoperative mortality and morbidity varies greatly worldwide and in the Russian Federation due to the heterogeneity of techniques and the level of tracking of postoperative results. To develop algorithms to standardize the surgical treatment of gastric cancer and its complications, as well as to improve the quality of further studies, a multicenter cohort prospective study GASTROSTAT was conducted to analyze postoperative complications and mortality after elective radical surgery for gastric cancer. The study was initiated by the Hertsen Moscow Oncology Research Institute, a branch of the National Medical Research Radiological Centre (NMRRC) of the Ministry of Health of the Russian Federation. 45 federal centers and regional oncologic dispensaries from 30 cities of Russia and the Republic of Belarus were invited to participate in the study. All consecutive patients with primary gastric cancer (carcinoma), including esophagogastric cancer (Siewert III), who underwent elective radical surgery (gastrectomy, distal or proximal subtotal resection, etc.) via open, laparoscopic or robot-assisted access between March 18, 2024 and September 18, 2024 were included in the study, regardless of additional drug (neoadjuvant, adjuvant, perioperative, intraoperative) or radiotherapy. The purpose of this article is to present our proposed study design and its features. This design will allow us to study 90-day rates of postoperative morbidity and mortality in patients undergoing elective surgery for gastric cancer, to form a unified structure, and to develop recommendations for the prevention and reduction of postoperative general and surgical complications.