Despite new techniques to investigate intestinal motility disorders the underlying etiologic and pathogenetic mechanisms remain uncertain in most cases. Years ago it was thought that in gastro-esophageal reflux disease the impairment of the lower esophageal sphincter is the only pathogenetic factor. In contrast to this recent studies ruled out that gastro-esophageal reflux disease seems not to be a monofactorial problem but has different pathogenetic mechanisms. The same problem has to be stated for the primary motility disorders of the esophagus. Although more often diagnosed in the last years due to more sophisticated diagnostic tools, the underlying mechanisms of the diseases are still poorly understood. In achalasia dilatation procedures seem to be the most promising therapeutic means, whereas the role of medical treatment in this disease has to be defined more clearly. Therefore a lot of work has to be done in the future to get a better basic knowledge of the motility problems of the gastrointestinal tract.