Mouse monoclonal antibodies against analogues of two mycotoxins ( deoxynivalenol ( DON) and nivalenol (NIV)) commonly found in cereal crops were isolated and used to develop an immunological detection assay. We immunized BALB/c mice with 4,15-diacetylnivalenol-3-O- hemisuccinate conjugated to keyhole limpet hemocyanin and isolated 21 hybridomas secreting monoclonal antibody (MAB) which reacted with 3,4,15-triacetylnivalenol (3,4,15-TANIV). These MABs were classified into two distinct types of reactivity against analogues of NIV and DON. Two monoclonal antibodies, KTM-205 and 208, were highly specific for 3,4,15-TANIV, whereas KTM-233, 239 and 240, cross-reacted with both 3,15-diacetyl deoxynivalenol ( 3,15-DADON) and 3,4,15-TANIV to the same extent. Acetylation under mild conditions can derivatize nivalenol and deoxynivalenol to 3,4,15-TANIV and 3,15-DADON, respectively. Thus the competitive indirect ELISAs for measuring nivalenol and deoxynivalenol were developed using these monoclonal antibodies. The detectable level of 3,4,15-triacetylnivalenol and 3,15-diacetyldeoxynivalenol was about 0.3 to 1000 pg/mL in buffer by the indirect competitive ELISA with KTM-240. Thus we have successfully generated useful MABs for an ELISA for the detection of nivalenol and deoxynivalenol in agricultural crops.