IN AN attempt to determine the true incidence of perforation of the gallbladder in a large series of necropsies, a review was made of 12,000 consecutive routine autopsies done at the Los Angeles County Hospital from April 1936 to January 1942. It is evident from the results of this large series of necropsies that the incidence and mortality of perforation of the gallbladder are much higher than heretofore generally believed. The argument for early operation for acute cholecystitis as a means of lowering the mortality from perforation is further strengthened by the presentation of an analysis of 105 cases of acute cholecystitis in which operation was performed at the White Memorial Hospital, Los Angeles, in the period between 1924 and 1944 and at the Glendale Sanitarium and Hospital, Glendale, Calif., in the period between 1927 and 1944. A vast amount of writing has been done on the subject of acute