Functional gastrointestinal disorders are characterized by chronic or recurrent symptoms, which are not explained by structural or biochemical abnormalities. These disorders seem to relate with abnormalities in motility and/or afferent sensitivity modulated by the central nervous system. There has been an improvement in the study of mechanisms of visceral pain, due to the development of animal models that reasonably mimicis human visceral pain. Recently, it appeared that visceral hypersensitivity or visceral hyperalgesia is related with the main pathogenetic mechanism of functional gastrointestinal disorders. Experimental balloon distention of the gastrointestinal tract in animal models has been established to reproduce pathologically-experienced pain in terms of intensity, quality and area of the sensation. Colorectal balloon distention in rat model with irritable bowel syndrome, is most widely used as an experimental stimulus to induce the visceral pain. Gastric distention in rat model is also used for the study of functional dyspepsia. Various routes of drug administration including intrathecal and intrarostroventral medullary injection have been developed for evaluation of visceral pain mechanism. Mouse model for colorectal balloon distention is now developing. (Korean J Gastroenterol 2001;38:77-82)