Objective: The incidence of gastrointestinal cancer is increasing day by day and is among the highest 10 cancer types in the world. This study was conducted to evaluate the effects of self-efficacy of patients with gastrointestinal system cancer on symptom clusters. Methods: This cross-sectional study was conducted with 105 patients treated for gastrointestinal system cancer in a hospital located in the south of Turkey. In the study, patients over 18 years of age without hearing or speech impairment were included. To determine symptom clusters, Latent Profile Analysis and comparison of self-efficacy scale items by symptom clusters were performed with Chi-square, ANOVA, and Kruskal Wallis test. Results: The mean age of the patients was 58.83 ± 13.1 years; of the patients, 37.1% had colon ca, 21.9% had rectum ca. The patients had higher mean scores of fatigue, pain, feeling distressed, feeling sad, dry mouth, sleep disturbance, loss of appetite and nausea in the last week. The patients had higher mean scores of fatigue, pain, feeling distressed, feeling sad, dry mouth, sleep disturbance, loss of appetite and nausea in the last week. Three symptom clusters were determined by latent profile analysis; high, moderate, mild. It was determined that the level of self-efficacy was high in the symptom cluster which is low symptom severity and number of symptoms ( p < .05). Conclusion: The number and the severity of symptoms are lower in patients with high self-efficacy perceptions.