The skin is a frequent site of pathological immune responses that can take place in the dermal and/or the epidermal compartments.These immunopathological reactions often occur towards innocuous antigens and may be the result of T cell-dependent and/or autoantibody dependent mechanisms. Defective immune regulation is increasingly recognized as very relevant in many skin and systemic immune-mediated disorders. In some instances (e.g., psoriasis and atopic dermatitis) genetic predisposition can affect also the capacity of keratinocytes to initiate or perpetuate inflammatory responses. A more precise understanding of the molecular and cellular mechanisms underlying each disorder may allow the identification of novel targets for more effective therapeutic strategies.