Thirty-two patients with chronic renal insufficiency (CRI) had oral cholecystography. Eleven of 15 patients (73%) with moderately advanced renal impairment had diagnostically inadequate single-dose cholecystograms. In contrast, all 11 patients on chronic hemodialysis had diagnostically opacified gallbladders following a single dose of contrast. Six other patients had biliary disease, either calculi (5 patients) or neoplasia (1 patient). These data suggest that CRI diminishes the likelihood of diagnostic gallbladder opacification, even in the absence of gallbladder disease, and that if the metabolic consequences of CRI are controlled by dialysis, the chances of diagnostic opacification are significantly improved (P less than 0.005). As oral cholecystography may not only result in inadequate opacification, but also carry the potential of renal toxicity, abdominal ultrasound should prove a safer and possibly more effective alternative in such patients.