Surveillance after curative resection for colorectal cancer is reviewed with special reference to the guidelines for colorectal cancer treatment issued by the Japanese Society for Cancer of the Colon and Rectum. The principal aim of postoperative surveillance in patients with colorectal cancer is to improve survival by early detection of a recurrence while it is still resectable. Meta-analyses from Western countries demonstrated that intensive follow-up after curative surgery improves survival. In Japan, more intensive follow-up programs have been performed routinely than in Western countries. Although the impact of intensive follow-up on survival has not yet been clarified in a large-scale study, unified follow-up programs are suggested in the guidelines, based on the results of a large-scale, retrospective, multicenter study. The relapse rate in patients with Stage II, IIIa, and IIIb colorectal cancer increased rapidly during the first 3 years and gradually during the next 2 years. The relapse rate at 5 years or later was less than 1%. The prognoses of patients who underwent curative resection for relapse were better than those who did not. Periodic follow-up for metachronous multicentric colorectal cancers should be recommended. Further studies will be necessary to validate the efficacy of intensive follow-up.