Background: The endoscopic measurement of sphincter of Oddi pressure is a technically difficult procedure requiring significant expertise. Intrabiliary pressure is technically easy to measure. Furthermore, since it is believed that the pathogenesis of pain in patients with sphincter of Oddi dysfunction is attributable to increased intrabiliary pressure, its measurement may be more clinically relevant than measurement of sphincter of Oddi pressure. Methods: Intrabiliary pressures were blindly measured in 54 patients who had sphincter of Oddi manometry for abdominal pain. Results: In all patients intrabiliary pressure was significantly higher in patients with sphincter of Oddi dysfunction than those with normal sphincter of Oddi pressure (19.6 ± 2.2 vs 9.6 ± 1.2 mm Hg; p < 0.01). These findings were similar when patients were stratified according to presence of intact gallbladder (19.3 ± 1.6 vs 8.8 ± 1.4; p < .001) and to patients without a gallbladder (20.1 ± 3.8 vs 12/1 ± 1.3; p = .034). There was positive correlation between intrabiliary pressure and sphincter of Oddi basal pressure. This correlation was significant both in patients with and without gallbladders. Conclusions: These data suggest that increased intrabiliary pressure may be a useful surrogate marker of sphincter of Oddi dysfunction. (Gastrointest Endosc 1996;44:696-9.)