Anal squamous cell cancer is most frequently a locoregional disease that is amenable to curative therapy in a majority of fit patients. Complete response rates after chemoradiotherapy (CRT) are good, with up to 75% of patients with no evidence of relapse on surveillance. Relapse is most frequently locoregional and is often amendable to salvage surgery with curative intent. Effective surveillance attempts to improve outcomes by identifying recurrent or persistent disease early, managing both acute and late toxicities, and offering reassurance to patients. This article explores the rationale and evidence for surveillance programs after definitive CRT.