While the complexity of the reflex responses of the alimentary canal to chemical stimulation is appreciated, detailed analysis of the receptor mechanisms has yet to be made. This gap in our knowledge remains in spite of recent progress in understanding of peripheral sensory mechanisms in other regions of the body and offers a continuing challenge to experimental skill. However, with several techniques already available for use in this area, the next few years may see a beginning to an understanding of gastrointestinal chemoreception.