Abstract: This study deals with the rapid diagnosis of grass carp (Ctenopharyngodon idellus) haemorrhagic virus by coagglutination test using antibody-sensi-tized staphylococci protein A (SPA COA), as well as the preliminary experimentaldata for the diagnosis of purified vius, cell-infected virus and tissues of infectedfish. The results obtained from the specific and sensitive detection and the electro-nic microscopic observation of the coagula, indicate that this rapid and simple me-thod, which requires no special apparatus and easy to perform in the basic unit, isprobably one of the valuable indexes for identifying the vaccine quality of grasscarp haemorrhage.