Background: The incidence of anal carcinoma in the United States continues to increase steadily, and infection with the human papillomavirus (HPV) is an established risk factor for the development of anal carcinoma. However, clinicopathologic characteristics of patients with metastatic squamous cell carcinoma of the anal canal according to HPV status have thus far not been defined. Methods: Records of patients treated for metastatic squamous cell carcinoma of the anal canal at the MD Anderson Cancer Center between June 2005 and August 2013 were reviewed. Patients were tested for the presence of HPV DNA by in-situ hybridization and/or the p16 oncoprotein by immunohistochemistry. Associations between the presence of HPV and clinicopathologic attributes were measured by calculation of odds ratios, and survival was estimated according to the Kaplan-Meier method. Results: Patients were followed for a mean of 50.2 months, and the mean age at diagnosis was 54.0 years. Among the 43 patient records reviewed, 39 tumors (90.1%) tested positive for the presence of HPV. Patients with HPV-negative tumors were more likely to have a strong (> 30 pack-year) tobacco history (OR=18.5, p=0.018) and were more likely to develop brain metastases (OR=2.0, p=0.04). A faint association was observed between Caucasian ethnicity and HPV-positive tumors (OR=8.8, p=0.06). Median survival from the time of diagnosis of metastatic disease was 42.4 months, with a trend towards a worse survival seen among patients with HPV-negative tumors (HR for death 4.9, p=0.09). Conclusions: Differences in HPV status and prior tobacco exposure may identify two separate populations of patients with metastatic squamous cell anal carcinoma with different clinicopathologic phenotypes. Our results are similar to prior published data in patients with squamous cell carcinoma of the head and neck in which patients with HPV-positive tumors demonstrate improved survival outcomes. Data from additional patients will be presented.