Polyvalent “O” and “H” antigens for the serodiagnosis of salmonellosis were described. These antigens are composed of Salmonella agglutinogens corresponding to the antigens of most salmonellae found under different climates. They were tested in 60 cases of salmonellosis, 52 persons immunized with T. A. B. vaccine, 47 patients with diseases often giving non-specific positive Widal tests and 56 persons who were not immunized nor had a story of salmonellosis. The antigens were more reliable for the diagnosis of salmonellosis than the routine set of typhoid, paratyphoid A and B antigens.