Introduction: Due to a lack of clear dietary guidelines, patients with inflammatory bowel disease (IBD) self-impose dietary restrictions based on their own nutritional experiences. The aim of this study was to investigate dietary perceptions and behavior in IBD patients. Materials and methods: A total of 82 patients (48 with Crohn’s disease and 34 with ulcerative colitis) participated in this prospective, questionnaire-based study. Based on a literature review, the questionnaire was developed to investigate dietary beliefs, behaviors and food exclusions during IBD relapses and remission. Results: The majority of patients (85.4%) believed that diet can be a trigger factor for IBD relapses, and 32.9% believed that diet initiates the disease. The majority of patients (81.7%) believed that they should eliminate some products from their diets. The most often-pointed-out products were spicy and fatty foods, raw fruits and vegetables, alcohol, leguminous foods, cruciferous vegetables, dairy products and milk. Most patients (75%) modified their diets after diagnosis, and 81.7% imposed food restrictions to prevent IBD relapses. Conclusions: The majority of patients avoided certain foods during relapses as well as to maintain remission of IBD, basing this on their own beliefs, inconsistently with current scientific knowledge. Patient education should be a key determinant in IBD control.