To the Editor.— In their recent editorial (1983;249:783), Craig and Clayman state that percutaneous transhepatic cholangiography (PTC) is preferable to endoscopic retrograde cholangiopancreatography (ERCP) in the examination of patients with obstructive jaundice shown to have dilated ducts on ultrasound. At a center like ours with a high success rate of cannulating the common bile duct, we believe that ERCP may offer advantages over PTC in some cases and be the procedure of choice in the evaluation of obstructive jaundice regardless of whether there are dilated bile ducts on ultrasound. First, ERCP allows inspection of the papilla of Vater and duodenum, which may be abnormal with ampullary or duodenal cancer. Endoscopic biopsy can be performed in these instances to give a definitive diagnosis. Second, ERCP allows visualization of the pancreatic duct, which may be advantageous in diagnosing pancreatic cancer and obstructive jaundice caused by chronic pancreatitis. In the occasional case of