In a case of gallbladder and common bile duct lithiasis, the selective cannulation of the cystic duct and gallbladder by a balloon catheter after endoscopic papillosphincterotomy fulfilled both diagnostic and therapeutic purposes. A choledochal stone was retrieved with the Dormia basket. The endoscopic dilation of the cystic duct by the balloon permitted spontaneous elimination of all the gallbladder stones.