The immune response of a group of patients with epidemical neuropathy and of controls was studied by the immunoblotting technique against proteins of the Coxsackie virus and the proteins of slow effect isolated in our laboratory. 13 sera of patients with epidemical neuropathy and 9 sera of controls were studied. Of the 13 sera studied, 8 (61.5%) recognized protein VPI and 2 sera (15.3%) protein VP0 of the strain 47.93. Of the 9 controls studied, 4 (44.4%) recognized protein VPI and 3 (33.3%) protein VP0 only. With the antigen prepared from the slow effect strain it was obtained a specific signal in 5 (38.5%) sera of patients and in 2 sera (22.5%) of controls. It should be stressed that in this last case the protein observed had a molecular weight of 41,300 D, and that its size was smaller than that of the preceding protein detected against the strain 47.93 was of 45,000 D.