Since the first description of the hog cholera bacillus by Salmon and Smith in 1885, many reports of food poisoning as well as of sporadic infection in human beings due to this organism have appeared. Twenty-one patients with Salmonella suipestifer infection have been treated at the Johns Hopkins Hospital since April 1933. In view of the relative frequency of this infection in Baltimore, it seems desirable to report these cases and to review the literature in order to determine more clearly the clinical manifestations of S. suipestifer infection in man. In 1902 Longcope published a report of two cases of human infection of a typhoid-like nature with leukopenia caused by a "paracolon" bacillus. Later studies by Ten-Broeck revealed that the organism isolated by Longcope belonged to the hog cholera bacillus group. Prior to the appearance of this article no infection due to this organism in human beings had been described.