The capacity of formalinized goose erythrocytes to be agglutinated in interactions with arboviruses was studied. Formalinized goose erythrocytes were found to be as sensitive as native erythrocytes, and were used successfully for diagnosis of arbovirus infections and study of the immune structure of the human population and animals. The superiority of formalinized erythrocytes is determined by the duration of storage (2 years of the observation period) withoug any change in the capacity for agglutination.