Melanin is an irregular light-absorbing polymer containing indoles and other intermediate products derived from the oxidation of tyrosine. Melanin is widely dispersed in the animal and plant kingdoms. It is the major pigment present in the surface structures of vertebrates. The critical step in melanin biogenesis is the oxidation of tyrosine by the enzyme tyrosinase. In vertebrates this enzyme is active only in specialized organelles in retinal pigment epithelium and melanocytes. In mammals melanin is formed as intracellular granules. Melanin granules are transferred from melanocytes to epithelial cells and form the predominant pigment of hair and epidermis. Melanin has many biological functions