The limited amount of research on Vibrionic Dysentery in swine may be attributed to the misunderstanding of the enteric diseases of this species, the failure to recognize the etiologic agents of the enteric conditions which nay result in fibrinonecrotic enteritis, the prevalence of hog cholera in certain countries, and the difficulties encountered in isolating Vibrio coli from affected animals and in experimentally transmitting this infection. Vibrionic Dysentery is a specific, acute or chronic, infectious, transmissible disease of swine characterized by a severe inflammation of the large intestine and diarrhea. The feces may contain mucus, blood or particles of croupous exudate but real bloody diarrhea is encountered only in a few instances. Hofferd (63) and Doyle (32) reported that the disease was first noticed in the United States in 1918. Vibrionic Dysentery was described in 1921 by Whiting, Doyle and Spray (133). Since then it has been reported from a number of different countries and has been regarded as a specific disease. In Ontario, Vibrionic Dysentery is probably the most important enteric infection of swine. Its primary importance is economic in regards to the loss of body weight and the setback of pigs, in addition to the mortality caused by the disease. The obvious lesions encountered are situated in the gastrointestinal tract, almost exclusively in the large intestine. The lesions most frequently seen are those of catarrhal inflammation. Lesions of hemorrhagic and fibrinonecrotic inflammation are also frequently observed. Neither constant nor significant gross changes are found in the other organs. Many names have been given to this condition by veterinarians and farmers throughout the years, including: hemorrhagic enteritis, hemorrhagic colitis, hemorrhagic dysentery, swine typhus, bloody dysentery, flux, bloody flux, bloody diarrhea, colitis, Dakota disease, bloody scours, black scours, necrotic enteritis, infectious enteritis, necro, swine vibriosis, vibrionic enteritis, swine dysentery and vibrionic dysentery. For clarity, the following work has been divided in three parts: The first part is a study of the gross and microscopic lesions of Vibrionic Dysentery as they are seen in natural cases in Ontario. The second part deals with details concerning the isolation and identification of Vibrio coli from naturally or experimentally infected pigs. The third part deals with the significance of Vibrio coli in the etiology of the disease in swine.