Much has been written about infection of the gallbladder, but a fairly extensive review of the literature failed to discover descriptions of infectious lesions of the gallbladder in the absence of stones. The present study of gallbladder lesions was undertaken with the purpose of determining by what processes some of the commonly observed lesions and pathologic states of the gallbladder are produced. At the outset it was thought that a correlation of bacteriologic and histologic examinations of the gallbladder would give this information but discrepancies soon became apparent. Bacteria were often cultivated from gallbladders that showed no lesions and obviously pathologic ones often yielded negative cultures. The micro-organisms cultivated were almost always intestinal or mouth bacteria and in surgical material, manipulation of the gallbladder and duct at the operation made it impossible to exclude contamination from the duodenum. Collateral study of the clinical histories, the operation notes of surgeons and