Autoimmune diseases have a multifactorial pathogenesis.

If many genetic factors, such as the role of major hystocompatibility complex, are called in cause for the risk of these diseases, many environmental factors are discovered as actors in the pathogenesis.

In this paper we evaluated the role of the exposition to UVB rays, the role of activation of vitamin-D and the development of autoimmunity. We also observed the role of toxic esogen agents in the air, with particular attention for exposition workers.

Finally, the role of cigarette smoking, and the development of particular autoantibodies such as rheumatoid factors and anti-cyclic citrullinated peptide in the pathogenesis of rheumatoid arthritis, are discussed.