In the cases of infectious hepatitis that has a complication of cholecystopathy, the author studied mainly its pathogenesis; and obtained the following results. 1. Out of 138 cases with hepatitis 33 cases (23.9%) had cholecystopathy as the complication. When these 33 cases are studied histologically by liver biopsy, periacinar form of chronic infectious hepatitis is found in 13 cases (39.3%), occupying the greatest percentage; followed by acute infectious hepatitis in 5 cases (15.2%), parenchymatous form of chronic infectious hepatitis in 4 (12.1%), posthepatitic cirrhosis in 4 (12.1%); and posthepatitic fibrosis in 2 (6.1%). On the other hand, judging cholecystopathy from various patho-histological forms, cholangiolitic hepatitis in 100%; periacinar form of chronic infectious hepatitis in 43.3%; posthepatitic fibrosis in 28.6%; parenchymatous form of chronic infectious hepatitis in 20%; posthepatitic cirrhosis in 11.9%; and acute infectious hepatitis in 11.8%. 2. Those showing biliary dyskinesia are mainly composed of the form revealing no marked changes in the liver biopsy (so-called posthepatitis syndrome) or the periacinar form of chronic infectious hepatitis. 3. Those having the complication of cholecystitis are more frequently found in acute infectious hepatitis and posthepatitic cirrhosis. 4. Generally even in the liver biopsy at the time of operation the infiltration of round cells and edema formation in portal region are characteristic traits of the common cholecystitis. 5. In the necropsy of infectious hepatitis likewise the liver and gallbladder are affected simultaneously; and the edema formation from the sublayer of mucous membrane to the sublayer of serous membrane and the congestion of capillary blood vessels with cell infiltration are the main common histological changes in the gallbladder. 6. When the antiserum obtained from the rabbit sensitized with dog abdominal organs (liver, gallbladder, duodenum, stomach, and rectal mucous membrane) as the antigen is injected into dogs, allergic cholecystitis can be induced in 100% of the animals with the use of gallbladder antiserum; in 80% with liver antiserum; in 60% with antiserum of rectal mucous membrane; and in 40% each with stomach antiserum or with antiserum of duodenal mucous membrane. In these instances intralobular and portal cell infiltration and edema formation in portal region can also be observed. 7. The characteristic traits of hepatitic cholecystopathy are the edema formation extending from the sublayer of the gallbladder mucous membrane to the sublayer of serous membrane and cell infiltration around blood vessels. As for the pathogenesis there seems to multiple factors; namely, dyscholia due to functional disturbances of the liver, the loss of the gallbladder motility due to invasion of inflammation inducing substances from portal tract through lymph ducts on serous inflammation, and also it is possible to be met with the secondary infection with an increase in the number of intestinal bacteria coexisting, and in some the involvement of allergic inflammation in gallbladder can be recognized.