Using a high-fidelity recording system, simultaneous manometric measurements of the sphincter of Oddi and duodenum were performed in 6 dogs. The sphincter of Oddi was a high-pressure zone with superimposed phasic activity. The tracings were analyzed according to the distribution of the peak-to-peak contraction intervals (PPI), and a multimodal distribution was consistently found with a basal mode of 3.5 s. If not occurring at this interval, the PPI would be a multiple of this value. These findings suggest that slow-wave control activity is present in the canine sphincter of Oddi. The origin of this control is still unknown.