The present invention relates to a method and kit for detecting antibodies in clinical samples of animals infected with equine infectious anemia virus using the immunodiagnosis with the recombinant viral antigen p26. The antigen was bound to solid supports (microtitter plates, tubes, beads or nitrocellulose papers or nylon) and reacted with the test serum. After incubation with conjugated anti-equine immunoglobulin-enzyme the reaction was revealed with a solution composed of the substrate of the enzyme used in the conjugate (cromogene). After development of the reaction (color formation) it was stopped with acid solution and measured. The immunoassay may be a direct second antibody immunoassay, a one or two step sandwich immunoassay.