Following radical surgery and adjuvant chemotherapy, patients with colorectal cancer should be monitored to evaluate treatment-related complications, detect recurrent metastatic lesions that can be radically resected, and detect early uninfiltrated heterochronic multiple primary tumors. The merits of closer postoperative follow-up and monitoring of patients with stage II or III disease have been demonstrated in several prospective studies and in three recent meta-analyses, the latter randomized controlled trials comparing low-intensity and high-intensity postoperative follow-up monitoring programs. Other recent studies that have influenced postoperative surveillance and follow-up programs for colorectal cancer include a meta-analysis that included a large sample of 20,898 cases from 18 trials of adjuvant colon cancer, which showed that 80% of tumor recurrences occurred within the first 3 years after radical surgical resection of the primary tumor; close postoperative follow-up has also been shown to benefit patients in stages I and IIa. There is another population-based report showing an increase in both surgical resection and survival rates for colorectal cancer with local recurrence or distant metastases, thus supporting closer postoperative follow-up and surveillance in these patients. Nevertheless, the optimal surveillance strategy after potentially radical colorectal cancer surgery remains controversial.