The method of synthetizing dispersions of gelatin-modified polyacrolein microspheres 1.5-2.5 micrograms in diameter, used as a solid-phase carrier for the preparation of immunodispersion diagnostica, has been developed. The possibility of using immunodispersion diagnosticum in the passive agglutination test with hyperimmune rabbit sera has been demonstrated. High activity and specificity of immunodispersion diagnosticum, combining methodological simplicity and rapidity characteristic of agglutination, has been shown.