Alfa Melanocyte Stimulating Hormone (-MSH) is the key factor in controlling melanogenesis through the activation of the G-protein coupled receptor MC1R. The interaction with the receptor activates the cAMP/PKA pathway and subsequently the Microphthalmia-associated transcription factor (MITF). Polymorphisms of the receptors are associated with fair skin. However -MSH exerts several other functions on the skin including control of cell differentiation, inflammatory response and oxidative stress and it also acts on non pigmented cells. Previously we have shown a correlation between the type and the amount of melanin synthesis and the expression of the antioxidant enzyme catalase. Moreover, we have shown how intermediates of eumelanogenesis induce keratinocyte differentiation whereas pheomelanogenesis is associated with an alteration of gap junction. These data suggest a role of melanogenesis in control of skin barrier functions. We have also recently discovered a new pathway of -MSH activity which involves the Peroxisome proliferator activated receptor - (PPAR-). This link exerts an influence on melanogenesis, proliferation and antioxidant expression and it is PI(4,5)P2/PLC beta pathway dependent. Lipid composition of the plasma membrane seems to possess a relevant role in this mechanism. These results suggest that skin phototype is the result of several mechanisms and it can be considered a biochemical fingerprint of individuals. The interaction of -MSH with nuclear receptors can explain the complexity of the process.