To explore or not to explore the common bile duct during a cholecystectomy is an alternative which must be resolved by all who perform this operation. The complications resulting from an error in judgement in this decision have been well pointed out.1,2 An example of the earnest desire to avoid such errors is the paper of Bartlett et al,3 who have studied the predictability of the presence of common bile duct stones on the basis of certain clinical variables. However, despite all such precautions, most authors agree that not only is the incidence of residual stones at least 10%,2,4,5 but 50% of choledochostomies prove not to have been necessary. In 1931 Mirizzi6 first proposed a new method for exploring the biliary tract during an operation which he called operative cholangiography. Experience with and without this technique has resulted in innumerable controversial publications2,4-9 and, as well,