Five hundred and ninety-four patients were consecutively admitted to an infectious disease unit over a 2-year period with a referral diagnosis of acute gastroenteritis or food poisoning. In 175 (29%) patients, gastrointestinal symptoms were associated with a condition other than gastrointestinal infection. Non-infective gastrointestinal disease was present in 90 patients, systemic infection in 50 and systemic disease in 35. Four illustrative case histories are presented to emphasize the need for a high index of suspicion if diseases such as malaria, septicaemia or appendicitis are not to be missed.