Metal-induced autoimmunity is a well established but poorly understood phenomenon. Recent work has begun to elucidate the molecular interactions of metal ions with immune cells and self-proteins. Metal-induced presentation of cryptic self-peptides emerges as a possible mechnism for activation of metal-specific T cells, challenging the hypothesis of a random polyclonal activation of T and B cells by metals. A preferential T-helper cell type 2 response is involved in metal ion induced systemic autoimmune disease.