The fungus Crinipellis perniciosa is the causal agent of Witches’ Broom disease, which is responsible for great losses in Latin American cocoa production. In Brazil, production in the main cacao-growing region of Southeastern Bahia has decreased up to 90%. The C. perniciosa genome project has led to identification of genes that encode proteins potentially involved in pathogenic processes, such as the Necrosis and Ethylene inducing Proteins (NEPs). This class of proteins was initially identified from the culture medium of Fusarium oxysporum, which showed the ability to induce necrosis in several dicotyledonous plants. We recently reported the existence of three putative genes encoding NEPs in C. perniciosa (NEP1, 2 & 3). We have cloned the genes coding for NEP1 and NEP2 from C. perniciosa and the homologous protein, NPP1, from Phytophtora parasitica (a phytopathogenic oomycete) and expressed them in Escherichia coli. We are currently characterizing these proteins using spectroscopic and hydrodynamic methods. All of the proteins present a high content of b-sheet (around 50 %) and a low content of a-helix (less than 10 %) as seen by circular dichroism. The degree of oligomerization was studied by dynamic light scattering and native polyacrilamide gel electrophoresis. NEP1 and NPP1 present a molecular weight of 74 kDa that correspond with a trimer and NEP2 presents a molecular weight of 26 kDa corresponding to a monomer. These results are intriguing because of the high amino acid sequence similarity among these proteins (75 % between NEP1 and NEP2, and around 52 % between NPP1 and both NEP1 and NEP2). All these proteins are able to induce necrosis and the production of ethylene when injected in plants of tobacco and cocoa.