Abstract. Immunotherapeutic drugs have radically changed the concept of therapeutic algorithms for systemic treatment of cancer patients. Immunotherapy has been associated with increased overall survival for a significant portion of the cancer patient population. This also means that the number of patients who require long-term support aimed at maintaining quality of life, functional status and social activity is growing. Rehabilitation, aimed at the individual needs of each person, is an integral part of recovery support. Objective. We assessed individual needs for rehabilitation measures, including analysis of nutritional and functional status, as well as the spectrum of electrolyte disturbances over time during immunotherapeutic treatment in cancer patients with advanced unresectable gastric cancer. Material and methods. The study included 21 patients with advanced gastric cancer, the average age of the participants was 62.2 years. Eighteen patients were treated with nivolumab + FOLFOX, 3 patients with pembrolizumab + FOLFOX. All patients underwent a course of physical therapy and nutritional support in the form of sipping between meals (nutrient mixtures) from preventive to therapeutic regimens. All patients were surveyed about nutritional risk and quality of life (EORTC QLQ C30) before starting treatment and after completing the immunotherapy line. Results. The quality of life of patients according to a dynamic survey (EORTC QLQ 30) was significantly better after six months of treatment. Despite the lack of significant significance of changes in the nutritional status of patients, a positive trend was noted — all patients with NRS3 improved their scores to NRS2 or NRS1. The feasibility of studying electrolyte status and individual electrolyte support as a necessary component of complex rehabilitation was also noted. The study is planned to be continued in a randomized trial on a larger sample, expanding the objective measures studied to include disease-free and overall survival, objective response to treatment, and duration of response to treatment.