The coagglutination test was used to identify Shigella boydii and Shigella dysenteriae. A trial was carried out with 13 native rabbit antisera to S. boydii and 10 antisera to S. dysenteriae, as well as with coagglutinating reagents prepared from these antisera. The use of coagglutinating reagents was shown to ensure the complete specificity of the results, to prevent the adsorption of diagnostic antisera and to decrease their consumption 50 times. The importance of the coagglutination test for the identification of shigellae is discussed.