Introduction: Eating habits can directly influence the individual's health status, and modulate the risk for Chronic Non-Communicable Diseases, such as cancer. Objective: To evaluate the diet quality of individuals undergoing cancer treatment. Methods: Descriptive cross-sectional study, with 50 adult individuals undergoing cancer treatment. To assess the diet quality, the 24-hour recalls were analyzed and the Diet Quality Index associated with the Digital Food Guide (DQI-DFG) was applied. The correlation of the DQI-DFG with the study variables was evaluated using Student's t-test, ANOVA and Pearson's correlation coefficient. Results: The study sample showed a predominance of females (68%), with a mean age of 58 years ± 12.0 years. The most common type of cancer among women was breast cancer (32%) and among men, intestinal cancer (6%). According to the DQI-DFG, most of the population studied was classified as having intermediate diet quality (66%), while 28% were classified as having low quality and only 6% as having good quality. Of the total sample, 48% of the patients were overweight and the most reported symptom was hyporexia, followed by nausea and vomiting. Conclusion: The diet quality of cancer patients was classified as intermediate, which indicates the need for interventions focused on dietary changes combined with the minimization of gastrointestinal symptoms to improve dietary intake and response to treatment. [ABSTRACT FROM AUTHOR]