Two patients with high-grade common bile duct obstruction from an impacted cystic duct stone are described. A low-lying cystic-choledochal duct juncture or contiguity of a large cystic duct with the common hepatic duct are usual preexisting anatomic conditions. Known as Mirizzi's syndrome, this uncommon phenomenon needs to be considered when clinical and intraoperative findings indicate obstruction of the common bile duct by stone, but bidirectional exploration of the common bile duct or location of an elusive calculus after choledochotomy proves unexpectedly difficult.