Among the four five-year periods from 1951 through 1970, the overall incidence of common duct calculi was relatively stable at 13% in 3,012 patients undergoing cholecystectomy with or without common duct exploration. The use of operative cholangiography rose progressively from 2.9% in the 1951-1955 period to 93% in the 1966-1970 group. This change was associated with a decrease in number of patients undergoing choledochotomy from 41% to 25% and by a striking increase in the number of positive explorations from 28% to 62% (1966 to 1970). No morbidity or mortality could be attributed directly to cholangiography. The recovery rate for calculi in patients who had choledochotomy for traditional criteria, to the exclusion of cholangiography, remained unchanged during these 20 years.