Patients with cystic fibrosis (CF) are deemed at risk of developing urinary incontinence (UI) due to repeated coughing and other factors causing increased pressure on the pelvic floor. Fecal incontinence (FI) is probably derived from the same mechanism, but only very few data are available on its frequency. The aim of this study was to determine the prevalence of FI in an adult population with CF. This retrospective study was conducted from January 2012 to June 2014. Patients were recruited from Marseille referral center for adult CF. They were asked to fill in a self-completed anonymous questionnaire for symptom assessment of UI and FI. Clinical data and a detailed history of CF were also recorded. A total of 155 out of 190 patients (92 females) of mean age 30.5±11years completed the survey. Seventy-three patients (47%) were lung transplanted. Forty patients (25.8%) reported FI with a mean St Mark's score of 4.9±2. Thirty-five patients (22.6%) reported UI. Eighteen patients (11.6%) reported both FI and UI. FI was significantly more frequent in older patients (34.27 vs. 29.54years, p=0.03) and in patients with associated UI (p=0.001). No relationship was found between respiratory, bacterial, nutritional status, transplantation, pancreatic status, practice of physiotherapy, delivery history, and FI. The high prevalence of FI in CF and its negative impacts need to integrate this symptom in the overall treatment of this pathology. The systematic early detection of FI may allow its rapid management and limit their consequences.