OBJECTIVE: Malnutrition-related disease particularly occur in patients with digestive system cancer. The administration of oral nutritional supplements (ONSs) is one of the methods of nutritional support recommended for oncological patients. The primary aim of this study was to assess the consumption-related aspects of ONSs among patients with digestive system cancer. The secondary aim was to assess the impact of ONSs consumption on the quality of life of these patients. PATIENTS AND METHODS: The current study included 69 patients with digestive system cancer. The assessment of ONSs-related aspects among cancer patients was conducted using a self-designed questionnaire, which has been accepted by Independent Bioethics Committee. RESULTS: Among all patients, 65% of participants declared that they consumed ONSs. Patients consumed various types of ONSs. However, the most common were protein products (40%) and standard products (37.78%). Only 4.44% of patients consumed products with immunomodulatory ingredients. Nausea was the most commonly (15.56%) observed side effect after ONSs consumption. Considering particular types of ONSs, side effects were the most commonly declared by patients who consumed standard products (p=0.157). The easy product availability in the pharmacy was noted by 80% of participants. However, 48.89% of patients assessed the cost of ONSs as not acceptable (48.89%). 46.67% of studied patients did not observe the improvement of quality of life after ONSs consumption. CONCLUSIONS: We have demonstrated that patients with digestive system cancer consumed various period, amount, and types of ONSs. Side effects after ONSs consumption occur rarely. However, the improvement of quality of life related to ONSs consumption was not noted in almost half of participants. ONSs are easily available in pharmacy.