The effects of chilli on gastrointestinal transit (gastric emptying, orocaecal transit, whole gut transit) were evaluated in eight healthy volunteers. In each subject, gastrointestinal transit of a standard test meal was measured on two separate days. On one of these occasions, 20 g of chilli powder was added to the meal. Gastric emptying was quantified with a radioisotopic technique, orocaecal transit by measurement of breath hydrogen concentrations and whole gut transit by counting the number of radio-opaque markers in the stool. The rate of gastric emptying was slower (P less than 0.05) and whole gut transit was faster (P less than 0.02) after the meal containing chilli, compared with the other meal. There was no significant difference in orocaecal transit. These results show that ingestion of chilli is associated with significant effects on gastric emptying and intestinal transit.