Objective To explore the relationship between activation-induced cytidine deaminase (AID) expression and melanoma invasion, metastasis and prognosis, and to evaluate the clinical significance of AID. Methods An immunohistochemical study was conducted to detect the expression of AID in paraffin-embedded tissue sections from 80 cases of melanoma and 23 cases of pigmented nevus. The relationship between the expression of AID and clinicopathological and biological features of melanoma was analyzed. Results The expression rate of AID was significantly higher in melanoma than in pigmented nevus tissue specimens(53.75%(43/80)vs. 13.04%(3/23), P<0.05). AID expression was closely correlated with lymphatic metastasis, Clark grade, depth of invasion and prognosis of melanoma (all P<0.05), but was of no significant difference among patients of different age, gender or nationalities(all P > 0.05). Of 19 melanoma specimens with BRAF mutations, 17 expressed AID, including all the 15 melanoma specimens with the BRAFV600E mutation. Conclusions AID may induce BRAF mutations in melanoma, participate in melanoma invasion and metastasis, and be correlated with melanoma prognosis.