A group of 16 patients with endemic pemphigus foliaceus under corticotherapy and still showing erythematous, papulous, verrucous, in general hyperpigmented lesions, which were characterized as cortico therapy resistant lesions, were studied. Such study was made through anatomopathology and direct immunofluorescence (DIF). Anatomopathologically, such lesions showed tendencies to epitelial hyperplasia and cleavage in variable levels at the epidermis what differs from the early lesions of EPF and coincides with the chronic injuries of the EPF of the pre-corticoid era. The DIF of the injured skin was positive for IgG in 93.75% of cases, as it happens in the early stages of EPF, being negative in a simple case in which there was not cleavage. In addition, in eight of those patients, the DIF of the healthy skin and the indirect immunofluorescence (IIF) were studied. The DIF was positive in three of these cases and in all eight the IIF was negative.