Shigella antibodies in 50 sera from healthy persons and 110 sera from patients with diarrhea were tested using microdetermination of the indirect bacterial hemagglutination with the polyvalent antigen, and the following results were obtained. A survey of sera collected from healthy persons revealed that 4% had positive titers, 1:64 or above, to Shig. flexneri, Shig. dysenteriae, and Shig. boydii, respectively, whereas all subjects were negative for Shig. sonnei, less than 1:64. Namely, 6 cases among the 50 subjects were positive. Among the patients with diarrhea, positive antibody titers were demonstrated in 29.9% against Shig. flexneri, 11.9% against Shig. boydii, 7.2% against Shig. dysenteriae, and 6.4% aginst Shig. sonnei, respectively. Therfoe, the total positive cases were 55.4% among 110 subjects. No correlation between Shigella and Salmonella antibody titers among patients with dirrhea was found.