The dark color around the anus is generally caused by the following factors: 1. As we age, the hormone level in our own body changes, resulting in melanin deposition around the anus, resulting in the darkening of the skin around the anus. This is a normal physiological phenomenon and does not require treatment. 2. Due to the many small folds at the anus and the frequent contraction and relaxation of the anal sphincter, as well as the long-term stimulation of the bowels, the blood circulation around the anus slows down, thus aggravating the color of the skin around the anus, which eventually appears brown or black. This symptom is also a normal phenomenon and does not require special treatment. 3, melanoma caused by the phenomenon of black skin around the anus. Melanoma is a malignant tumor, once formed will cause the skin cells around the anus to appear black, and cause greater damage to the patient’s health, need to be treated by surgical removal.