We investigated fasting gallbladder volume and gallbladder emptying in response to a fatty meal in 20 patients with asymptomatic gallstones and compared the results with findings from healthy controls. Compared with control subjects without gallstones, the majority of patients with gallstones exhibited a higher resting gallbladder volume, less fractional emptying after a fatty meal, and a higher postmeal residual volume. These abnormalities all appeared to stem from an abnormally high resting gallbladder volume. Whether the increased gallbladder volume and decreased postprandial fractional emptying in the gallstone patients represents a primary or secondary abnormality remains to be determined. The results suggest that in some patients decreased gallbladder contractility may contribute to gallstone development or proliferation.