Abstract: Monoclonal antibodies (MAbs) useful in the serological detection and identification of rice blast were produced by hybridoma cells formed from fusions of myeloma cells with splenocytes from BALB/c mice immunized with an extract of a liquid culture fluid of an isolate of Pyricularia grisea race IB-49. These MAbs reacted similarly with the antigens in various serological techniques used, and did not cross react with any unrelated fungal isolates representing 11 genera, but reacted positively with all 20 races or isolates of P. grisea. The MAbs could detect homologous antigen at about 60 ng fungal protein/ml and a 5-fold dilution of the extracts of infected rice tissue by ELISA. In accordance with another embodiment of the present invention, hybridoma lines secreting antibodies positive for the immunogen and negative for healthy rice tissue were selected from three independent fusions of NS-1 myeloma cells with splenocytes from mice immunized with crushed conidial suspensions of P. grisea race IB-49.