The objective of this study was to examine the in vitro responsiveness to cholecystokinin-8 of gallbladder muscle strips from patients with gallstones and to correlate the findings with preoperative ultrasonographic studies of gallbladder contractility. The response of gallbladder muscle strips to cholecystokinin-8 of patients with noncontracting gallbladders was significantly reduced in comparison to that of patients with gallstones whose gallbladders contracted in response to fat.