A novel variant of endemic pemphigus foliaceus (EPF) was described among individuals in an area surrounding El Bagre, Colombia, South America. The population in this rural mining community is exposed to high environmental levels of mercury, used for gold extraction, as well as other minerals, metalloids, and trace elements (e.g., quartz, rutile, granite, magnetite, and almenite) and ultraviolet radiation. Fifty con-trol subjects and fifty EPF patients in the endemic area were examined for the presence of mercury in skin biopsies and hair, using autometal-lographic and mass spectroscopic analyses, respectively. Simultane-ously, serum levels of IgE were measured, and cutaneous tests for hy-persensitivity reactions were performed. Using autometallography, mercuric sulfides/selenides were detected in 14 of 51 skin biopsies dis-tributed similarly in the control and patient groups. However, signifi-cantly higher serum IgE levels and mercury concentrations in hair, urine, and nails were found in patients compared with controls. Mi-croscopic analysis revealed mercuric sulfides/selenides concentrated within and around the sweat gland epithelium, as well as in dendritic cells. Five skin biopsies from EPF patients and five from controls that tested positive for the presence of mercuric sulfides/selenides by autometallography were randomly selected for electron microscopic analysis. This analysis revealed a mixed electron-dense and electron-light material closely associated with desmosomes in patients. How-ever, there were intracellular vesicles containing an amalgam of elec-tron-dense and electron-light materials only in the EPF patients. Thus, EPF-affected individuals are exposed to high levels of environmental mercuric sulfides/selenides and other elements. This is the first study reporting mercuric sulfides/selenides in skin biopsies from people liv-ing in a focus of EPF, and these compounds may play a role in the pathogenesis of autoimmunity.