PURPOSE: To evaluate the incidence of GB opacification, seen at CT, by contrast media injected a few hours earlier in adults with normal renal function and to assess the clinical significance of the opacification. MATERIAL AND METHODS: Seventeen patients with normal renal function were included in this study. Contrast enhanced CT scan was performed 4-13 hours after intravenous urography. As a control group, 17 patients in whom contrast media was not used in recent three days were included. The incidence of GB opacification and CT number of the GB were compared between 17 study patients and 17 control patients. RESULT: GB opacification(either homogeneous opacification or layering of contrast media and bile) was seen in 16 of 17 study patients(94%). GB was not opacified in any one of the control group. The mean CT number of GB was 174 HU in study patients, and was 27.3 HU in control patients. CONCLUSION:GB opacification seen at CT several hours after injection of water soluble contrast media seems to be a physiologic phenomenon, and that phenomenon should not be considered as a vicarious excretion due to impaired renal function.