The genetic diversity of Crinipellis perniciosa, the causal agent of the broom-of-witch, was evaluated considering the adaptative ability of different genotypes, according to the different hosts and geographic localization. Policlonal antibody was used to show the presence of the protein bands of C. perniciosa in gel of eletrophoresis of total proteins. Five isolates of this fungus from different hosts (Theobroma cacao L., Solanum cernuum, Solanum lycocarpum, Solanum paniculatum, and a Liana) from two different States of Brazil (MG and BA) were studied. The technique used was the Western Blot, applying two enzymatic systems - the alkaline phosphatase and the peroxidase. The first, where the dyes BCIP (5-bromine-4-chlorine-3-indol phosphate - B6274) and NBT (Nitro blue tetrazolium - N5514 Sigma) were used, was more satisfactory, since the policlonal antibody recognized bands with molecular weight lower than 30 until 94 KDa. The second method (peroxidase system), was stained with 4-Chloro-1-Naphthol, and it did not provide a good definition of the protein bands. This disturbed visualization of the marked bands became difficult their characterization. Therefore, the policlonal antibody and the Western Blot using the phosphatase system was efficient in the recognition of a protein band common to the several isolates of C. Perniciosa studied. This protein can be used for the production of monoclonal antibodies that are specific for such pathogen and they can aid epidemiologists in the process of qualification and quantification of the disease, reducing the focos of the disease in the main producing regions of cacao. So that, it is of great economic interest. Financial Support: CAPES