Twenty-eight patients with proven bile duct stones were evaluated during either operative or T-tube cholangiography. Two radiographs were obtained for each patient without changing patient position between films. The first was performed with low peak kilovoltage (75-80 kVp) and 15% iodinated contrast medium and the second with high kVp (110) and 38% iodinated contrast. Seven radiologists evaluated the radiographs individually and in matched pairs for ductal filling, ductal penetration, motion unsharpness, overall quality, and stone detectability. The high-kVp radiographs were rated significantly better overall than the low-kVp studies (p less than 0.001) for all five criteria. In the second evaluation, which compared the pairs from the same patients, the 28 high-kVp radiographs were considered superior to the 28 low-kVp studies by the radiologists in almost two-thirds of the comparisons (ductal filling, 68%; penetration, 59%; less motion unsharpness, 65%; overall quality, 77%; stone detection, 62%). On the basis of the results of this study, high-kVp technique with full-strength contrast medium for operative and T-tube cholangiography is recommended.