Background: Despite the importance of a gluten-free diet (GFD) in the management of celiac disease (CD), non-adherence is quite common and varies in different societies. The aim of this study was to survey adherence to a GFD and identify the barriers in the adult celiac population in Shiraz. Materials and Methods: In this cross-sectional study, the patients diagnosed with CD were determined through serum levels of tissue transglutaminase IgA (tTg-IgA) and immunoglobulin A (IgA). In patients with positive anti-tTG, small bowel biopsies were taken. A gastroenterologist routinely assesses CD patients at Shiraz Celiac Clinic. Also, an expert general practitioner describes a list of forbidden food to patients. Adherence to a gluten-free diet was evaluated using interview and tTg-IgA level. Results: Adherence to a gluten-free diet was 58. 2% among 170 participating patients aged 15 to 71 years. There was no significant difference in sex (P = 0. 730), current age, and age at the time of diagnosis (P > 0. 05) between the adherent and non-adherent groups. However, the adherence among the unemployed (P = 0. 036) and highly educated ones was significantly higher than others. More patients adhered to the gluten-free diet for 1-3 years (63. 7%), so after three years, less adherence was seen (50%). The most reason for non-adherence was lack of proper access and labeling, cost, and feeling different from others. Conclusion: Advances in the catering/food industry, increasing economic support and awareness about CD, GFD, and gluten-free products, as well as removing barriers such as inaccessibility and cost, can improve adherence to a GFD.