Malignant melanoma is the most common cutaneous cancer after squamous cell carcinoma and basal cell carcinoma of the skin. Oral malignant melanomas are quite rare and are diagnosed at later stages. Oral mucosal melanomas commonly occur on the palate and the maxillary mucosa. The pathogenesis and clinical behavior of oral melanoma is different from that of cutaneous melanoma. The grading and histopathological, immunohistochemical (IHC) markers (S100 & Human melanoma black–45) for diagnosing oral malignant melanoma has been elobrated in this review