Primary malignant melanoma has a wide range of diseases, accounting for 1%-2% of all malignant tumors. It occurs mostly in the skin, and secondly in the eye and the anal canal rectum. Anal canal rectal malignant melanoma (ARMM) is clinically rare and has a high degree of malignancy. In the 2651 cases of colorectal malignant tumors collected by our hospital from January 1999 to January 2009, only 17 cases were pathologically confirmed as anal canal rectal malignant melanoma.