In order to gain insight into the possible mechanisms involved in gallstone formation in colectomized ulcerative colitis patients, we studied gallbladder motility by means of ultrasonography in three groups of subjects: controls (N = 40) and ulcerative colitis patients without (N = 30) and with (N = 20) colectomy. Impaired gallbladder emptying after a liquid fatty meal stimulus was observed in ulcerative colitis patients with colectomy compared with those obtained in ulcerative colitis patients without colectomy and controls (P = 0.001). The maximum percentage of gallbladder emptying also, was significantly lower (59.8%) than those seen in ulcerative colitis patients without colectomy (74.5%) and controls (77.8%) (P = 0.001). Diminished gallbladder emptying with ensuing stasis might be a contributory factor to the increased prevalence of gallstones in colectomized patients.