Biliary dyskinesia is a rare disease and is defined as a primary disorder of sphincter of Oddi (SO) tonic/phasic motor activity without evidence of a structural narrowing of part or all of the SO segment. It is suspected when a patient, usually a woman, presents with biliary-type pain in the absence of a structural cause for such pain. Some authors classified SO motor disturbances into two broad categories. papillary stenosis: defined as a structural narrowing of the SO segment, and biliary dyskinesia. But because of the difficulty in clearly separating these two clinical entities, this syndrome is sometimes referred to such as SO dysfunction. Even though various tools to diagnose biliary dyskinesia have been developed, such as simple ultrasonography and ultrasonography after a fatty meal or cholecystokin administration, cineradio-graphy, ERCP, nuclear scintigraphy and biliary manometry, ERCP and biliary manometry are still considered as the "gold" standards. In Western countries, the number of reports of biliary dyskinesia confirmed by manometry have tended to increase recently, but it was known to be absent up to now in Korea. We report two cases of biliary dyskinesia confirmed by manometry who had suffered from recurrent biliary colic and showing normal findings on ERCP and ultrasonography without evidence of structural lesions. On biliary manometry, the basal and peak pressures of SO phasic contractions were markedly elevated and the frequencies of the phasic wave also increased (tachyoddia). After endoscopic sphincterotomy was performed for the purpose of treatment, a remarkable decrease in basal and peak pressure of SO phasic contraction was noted and the subjective symptoms were disappeared campletely.