Autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) predominantly affect women and are characterized by widespread immunologic abnormalities. These diseases involve multiple organs including the skin, joints, lung and kidney, as well as the peripheral and central nervous systems. Significant progress has been made in elucidating the role of several loci and genes in the pathogenesis of autoimmune diseases. In addition to the studies of genetic factors involved in the pathogenesis of autoimmune diseases, progress has also been made in identifying environmental factors involved in their pathogenesis. Although the etiology of autoimmune diseases is not yet fully understood, both genetic and environmental factors have been identified and an interplay between predisposing genetic factors and environmental conditions has been suggested in the triggering of the disease manifestation. Therefore, an overview of the environmental factors involved in the pathogenesis of autoimmune diseases could be quite useful for all researchers in the world. In this review, we discuss the historical and recent findings on the possible role of environmental factors such as sex hormones, viral infections, microbiome, ultraviolet radiation, cigarette smoking and alcohol consumption in autoimmune diseases.