534 Background: Survival of cancer patients is increasing. Therefore, there is a need to evaluate long term complications in cancer survivors. There is no data on second primary malignancies in anal cancer. This study was conducted to evaluate second primary malignancies in patients with anal carcinoma. Methods: We selected adult patients diagnosed with anal cancer from National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) 13 database We calculated the risk of second primary malignancies in the anal cancer patients using multiple primary standardized incidence ratio (MP-SIR) session of SEER*stat software. Results: Among 7,661 patients with anal carcinoma, 3,196 were men and 4,465 were women. Median follow up duration was 87 months (range: 7-239 months). Median age at the time of diagnosis of SPM was 69.33 yrs (range: 34-103 yrs). Median latency for SPM was 52 months (range: 6-219 months). A total of 675 patients (9.07%) developed 747 second primary malignancies, with an observed/expected (O/E) ratio of 1.41 (95% confidence interval =1.32-1.52, p<0.001), and an absolute excess risk of 55.36 per 10,000 populations. Significant excess risks were observed for oral cavity and pharyngeal tumor, rectal and anal canal tumor, laryngeal tumor, lung and bronchial cancer, Kaposi sarcoma, hematologic malignancies, ovarian, vaginal, and vulval tumors. Conclusions: The risk of second primary malignancies in adult patients with anal cancer is significantly increased compared to general population.