PRINCIPLES: Ulcerative colitis (UC) and Crohn's disease (CD) are chronic relapsing disorders with significant implications for health care. The latest epidemiological data for Switzerland were prospectively collected in 1971. METHODS: A prospective nationwide survey over a period of five weeks was initiated by IBDNet.ch and a questionnaire sent to all gastroenterologists in hospital or private practice. RESULTS: The response rate was 42% (85/204). 930 patients were recorded, 505 (54.3%) had CD, 425 (44.9%) UC, male/female ratio was 47 vs. 53%, mean age 44 +/- 15.8 years (standard deviation, SD). Median duration of disease was 84 months (mean 101 +/- 3.15 SEM). In CD, intestinal involvement was colitis in 135 (26.7%), ileitis in 142 (28.1%) and ileocolitis in 228 (45.2%) patients. In UC, (n = 425) pancolitis was present in 182 (43.5%), left-sided colitis in 140 (33.6%) and proctitis in 95 (22.9%) cases. Diarrhea was the main symptom (52.8%; CD/UC: 47.5% vs. 59.2%; p < 0.001), as well as abdominal pain 35.8% (CD/UC: 48.5% vs. 20.1%; p < 0.001), rectal bleeding 27.8% (CD/UC: 8.4% vs. 51.8%; p < 0.001). Weight loss was reported in 12.2% (CD/UC: 14% vs. 9.8%), anemia in 15.1% ( CD/UC: 14.8% vs. 15.3%). The mean number of medications per patient was 2.1 (+/- 1.2SD), CD/UC 2.4 vs. 1.9 (p < 0.001). 5-ASA preparations per os were used in 74%, topical treatment in 18% in both groups. Corticosteroids CD/UC 56.5%/54%, oral or topical budesonide (CD/UC: 19% vs. 16%; CD/UC: 1.9% vs. 2.1%). Antibiotics (18%) or immunomodulatory therapy, as well as infliximab, was similar in both groups. Inflammatory bowel disease related surgery was performed in 233 (25.4%): resection of stenosis or in fistula 132 (14.2%), colectomy (total and subtotal) in 70 (7.5%), colostomy in situ in 21 patients (2.3%). Extraintestinal manifestations occurred in 36.6%, significantly more in patients with CD vs. UC: 25% vs. 16% (p < 0.001). Arthritis 18.6% (CD/UC: 22.6 vs. 13.7%, p < 0.001) and osteoporosis were recorded in 9.7% (CD/UC: 13.65 vs. 4.8%, p < 0.001). Skin and eye involvement was seen in 6.3% and 2% respectively (CD/UC: 7.8 vs. 4.5% and 3.1 vs. 1%, p = n.s.). CONCLUSION: In conclusion, we attempted to characterise the patients with IBD seen by specialist gastroenterologists in Switzerland. The ultimate goal would be to set up a national cohort study to collect long-term data, which could be useful for epidemiological studies in patient and health care management, as well as for therapeutic intervention studies and basic research.