This study was carried out on a total number of 593 animals affected with heterochromia iridis, as well as 45 normal and 85 heterochromic enucleated eyeballs. Classification of heterochromia iridis, morphology of normal and heterochromic irises and histology, ultrastructure, and scanning electron microscopy were discussed in this study. The result of the present study indicated that, the incidence of heterochromia iridis in buffaloes was 7.62% including two types, bilateral and unilateral. Both of them were recorded in different forms of complete and partial heterochromia iridis. Iris hypoplasia was evident in all cases of heterochromia iridis. The color of the anterior surface of normal iris was bicolored while in heterochromic iris was bicolored, tri-colored or tetracolored. The histological structure of the iris in normal and heterochromic cases was the same except in pigment distribution.