Allergic contact dermatitis is induced by chemicals or metal ions. A hallmark of this T cell mediated skin disease is the activation of the innate immune system by contact allergens. This immune response results in inflammation and is a prerequisite for the activation of the adaptive immune system with tissue-specific migration of effector and regulatory T cells. Recent studies have begun to address in detail the innate immune cells as well as the innate receptors on these cells and the associated signaling pathways which lead to skin inflammation. We review here recent findings regarding innate and adaptive immune responses and immune regulation of contact dermatitis and other skin diseases as well as recent developments towards an in vitro assessment of the allergenic potential of chemicals. The elucidation of the innate inflammatory pathways, cellular components and mediators will help to identify new drug targets for more efficient treatment of allergic contact dermatitis and hopefully also for its prevention.