Summary A double-antibody sandwich elisa (das-elisa) was developed for detection of avian influenza virus (aiv) antigen. A monoclonal antibody to the viral nucleoprotein (np) was used to coat the elisa plates. A direct das-elisa and an indirect das-elisa were evaluated. In the direct das-elisa, monoclonal antibody to the aiv np conjugated with horseradish peroxidase was used. The direct das-elisa was evaluated for its sensitivity to detect purified np; this procedure detected as little as 0.1 ng. In the indirect das-elisa, rabbit np antibody and horseradish peroxidase-conjugated goat anti-rabbit immunoglobin were used as primary and secondary antibodies, respectively. The indirect das-elisa was evaluated for its ability to detect the aiv antigen in tracheal and cloacal specimens from turkeys inoculated with aiv. Results of indirect das-elisa were compared with those of conventional virus isolation. Percentage agreement between indirect das-elisa and virus isolation in aiv-positive samples was found to be 76.1% and, in aiv-negative samples, it was found to be 82.1%. These results in dicate that the das-elisa might be a viable alternative to virus isolation because of its rapidity, compared with virus isolation.