A review of the literature on gastrointestinal epidemiology during the last 25 years shows a comprehensive contribution from Danish studies. This is partly explained by very favourable conditions in Denmark for epidemiological research, due to various valid registers and a long tradition for longitudinal population and patient cohorts. Data are presented on prevalence, incidence, demography, clinical risk factors, clinical course, and prognosis of various gastrointestinal disorders. Main emphasis is put on Danish studies, which are compared with international results. Present possibilities for prophylaxis against gastrointestinal diseases and delimitation of treatment of benign diseases are discussed. It is expected that research within gastrointestinal epidemiology in Denmark will increase in the coming years.