This chapter discusses the possible biomedical applications that melanotropic peptides might serve in biology and medicine. α-Melanotropin is the physiologically relevant hormone controlling melanin pigmentation of the skin in vertebrates. Melanotropins are involved in the etiology of several of disorders, but they might also be used to alleviate some of these pigmentary problems. The treatment of metastatic malignant melanoma has been unsatisfactory. Dacarbazine and combinations of dacarbazine with vinblastine, bleomycin, and cisplatin has been the mainstay of therapy, although most response rates have not exceeded the range of 20 to 30%. Hyperpigmentation is, in fact, a so-called "cardinal symptom" of Addison's disease. Hypomelanotic disorders problems arise from an underproduction of melanin by melanocytes. The chapter demonstrates that certain melanotropin analogs cause a prolonged activation of melanoma cell enzyme activation after only a short period of exposure to the cells. The conformationally restricted melanotropin α-melanophore-stimulating hormone was also resistant to inactivation by sera and was quite resistant to α-chymotrypsin and trypsin.