The routine use of peroperative (pre-exploration) cholangiography was prospectively studied in 433 consecutive patients undergoing elective cholecystectomy. Satisfactory peroperative cholangiography was achieved in 396 patients using a C-arm image intensifier with image retention facility. Clinical indications for exploration of the common bile duct were noted for each patient but the decision for choledochotomy was determined by the cholangiographic results. Two hundred and forty-nine (63 per cent) patients had no clinical indications for duct exploration and cholangiographic findings were all normal. Of the 147 patients with positive clinical criteria, 39 (9.8%) had abnormal cholangiograms and required exploration of the common bile duct. In three patients duct exploration was negative giving a false positive rate of 0.73 per cent. The use of the image intensifier allowed dynamic study during cholangiography and optimum evaluation of the duct system. The results support the view that peroperative cholangiography could be restricted to patients with clinical indications for exploration of the common bile duct.