Primary anal melanoma is rare and aggressive malignancy. The disease is undetected or mistaken for a benign polyp or haemorrhoids thus patients commonly present with advanced, even metastatic disease. Unlike cutaneous melanoma, anal melanoma has no known risk factors.  Extracutaneous melanomas require special consideration due to their late diagnosis and consequently poor prognosis. Extracutaneous melanomas are considered to be biologically more aggressive than their cutaneous counterparts. Surgical excision remains the cornerstone of therapy. This case is reported because of the rarity of the disease in anal canal found in an 65 year  old male who was managed with diversion sigmoid loop colostomy: to relieve obstruction.