Heavy metal pollution still represents a primary concern regarding human health. Recently, it become evident that the contribution of heavy metals extends far beyond their accepted role in allergic diseases, and that they may play a more extensive role in a variety of other diseases. Several lines of evidence indicate that heavy metals have a key role in the induction or exacerbation of several autoimmune diseases (AD). Moreover, the association between exposure to heavy metals and the signs of autoimmunity are supported by some studies. The mechanisms by which heavy metals induce the development of AD are not yet fully understood. Our objective here is to highlight the association of exposure to some heavy metals and AD. In addition, we present recent results showing the possible alterations in Th1/Th2 reactivity by some heavy metals, which may constitute the trigger for the incidence of autoimmunity in susceptible individuals.