Investigators will create the first web-based Hong Kong inception cohort database. Via the web registration investigators intend to form a new prospective, uniformly diagnosed, population-based inception cohort of patients with IBD. Physicians, gastroenterologists, family doctors, surgeons and pathologists in our study area will be notified repeatedly about the study by letter, telephone, internet, personal visit of the investigators, and encouraged to inform investigators of every possible new case of IBD (persistent or relapsing diarrhoea, blood and/or mucus in the stools for more than three weeks, or abdominal pain and weight loss). Endoscopic, pathology and radiology records will be canvassed repeatedly for likely cases, both electronically and manually. By these methods investigators intend to capture over 90% of possible cases. New patients will be included during a five-year period, 01.04.2011 - 31.03.2016, followed by a five year follow-up period until 31.03.2021. All patients are required to meet the diagnostic criteria for IBD on the basis of clinical symptoms, endoscopic or radiological evidence or mucosal biopsies. Infectious gastroenteritis, tuberculosis, entamoeba and cancer have to be ruled out. The web-based Database application will be used for online registration of the various registration forms and questionnaires (see list of additional materials), and the database is located on a central secured server.