Criteria for diffuse oesophageal spasm(DOS) are dysphagia and chest pain with oesophageal manometry showing retention of peristalsis with the presence of synchronous contractions in response to wet swallows. Because of the intermittent nature of the symptoms, edrophonium was used as a provocative agent to increase diagnostic yield. Three hundred and ninety-six patients underwent transnasal manometry using a Gaeltec system of six internal transducers arranged at 5 cm intervals from the catheter tip; the majority of these patients received 10 mg edrophonium as an intravenous bolus. Reproduction of symptoms with typical manometry of DOS indicated a positive provocation test. There were no significant side effects. DOS was diagnosed in 34 patients who had either the typical manometry or a positive provocation test. Thirty of these patients received edrophonium. Twenty patients had baseline manometry which was diagnostic and ten of this group had a positive provocation test. The remaining 10 patients, who had normal baseline manometry, had positive provocation tests following the injection of edrophonium. Without edrophonium provocation testing, about a third of patients would not have been diagnosed as having DOS.