Recent advances in the investigation of brain-gut interaction in irritable bowel syndrome (IBS) were reviewed. Brain is suggested to play an important role in the pathophysiology of IBS on the basis of the following evidence. (1) Stress often induces major symptoms of IBS patients (Drossman et al., 1982), simultaneously with colonic hypermotility (Fukudo et al., 1987) or dysmotility of the small intestine (Kumar et al., 1985). (2) IBS patients rarely express symptoms or small intestinal dysmotility during sleep (Kellow et al., 1990). (3) IBS patients complain of more pain with balloon distension of the colon or rectum than normal controls; visceral perception is enhanced in IBS (Whitehead et al., 1990). (4) IBS patients often show psychoneurotic symptoms and extra-colonic somatic symptoms (Young et al., 1976). (5) There are some animal (Williams et al, 1987) or human (Dinan et al, 1990) experiments which indicate the possible involvement of brain peptide or brain monoamine in IBS. (6) Dysrhythmia or increased beta power in electroencephalogram is observed more often in IBS patients than in the normal controls (Fukudo et al, 1991) in addition to abnormal REM sleep in IBS patients (Kumar et al., 1992). These observations support our hypothesis that not only the gut but also the brain show dysfunction and exaggerated responsivity to the stimuli in IBS. Further research on brain-gut interaction in IBS is warranted.