Cisapride, the prototype serotonergic agent, evolved from a body of research that defined the key roles of serotonergic receptors in gastrointestinal motor and sensory function. Impressed by its in vitro properties and encouraged by clinical trial data, cisapride became the drug of choice for the treatment of a wide range of motility disorders and clinicians appeared impressed by its efficacy and comfortable with its side-effect profile. Once serious cardiac events began to be reported in association with cisapride therapy, dark clouds rapidly gathered and soon enveloped the drug, leading to its widespread withdrawal from markets. What lessons can we learn from the story of cisapride? How can its brief but spectacular rise and equally sensational demise inform the development of new drugs which are so sorely needed in the management of motility and functional gastrointestinal disorders? This review explores the background to the development of cisapride, its history in clinical trials and the experience with adverse events and, in so doing, attempts to identify lessons for the future in the therapeutics of enteric neuromodulatory drugs.KEY WORDS: cisapride, gastroesophageal reflux, gastrointestinal motility, gastroparesis, prokinetic, serotonin.Cisapride, introduced worldwide in the 1990s, is a serotonin 5-HT4 agonist with 5-HT3 antagonist activity that stimulates the release of acetylcholine from postsynaptic neurons in the enteric nervous system. It therefore had quite widespread prokinetic effects throughout the gastrointestinal tract: stimulating salivary secretion, increasing esophageal peristaltic amplitude, augmenting lower esophageal sphincter pressure, enhancing gastric emptying and stimulating small bowel and colonic transit. It was, however, devoid of antidopaminergic and direct cholinomimetic effects; the former avoiding the central nervous system and hyperprolactinemia-related side effects of metoclopramide, the latter avoiding the bladder and other side effects of traditional cholinergics, such as bethanechol. Though ultimately employed in a wide range of motility disorders from gastroparesis and pseudo-obstruction to colonic inertia, cisapride was actually approved by the Food and Drug Administration (FDA) in the USA for nocturnal heartburn based on the results of pivotal clinical trials. In primary care, cisapride soon came to be prescribed, either on its own or in combination with a histamine H2 receptor antagonist or a proton pump inhibitor, for a range of upper gastrointestinal symptoms including heartburn and dyspepsia. Its use was especially advocated for children with gastroesophageal reflux disease (GERD) based on the premise that dysmotility was predominant in the etiology of reflux in this patient population. Though trials in gastroparesis did not always show a consistent relationship between symptom improvement and an enhanced gastric emptying rate,