Patients who undergo a potentially curative treatment of colorectal cancer are at risk of local recurrences, distant metastases, and metachronous neoplasms. Accordingly, these patients typically undergo a multimodal oncological surveillance aimed to detect relapses early, with an expectation of a higher rate of radical retreatments and better overall survival. Despite much research, the optimal diagnostic panel and the intensity of surveillance have not been well established. Evidence indicates, however, that more intensive follow‑up is unlikely to improve survival after a curative colorectal cancer surgery, chiefly due to the scarcity of recurrences suitable for salvage treatment. Typical surveillance recommended by guidelines includes regular physical examinations, computed tomography scans, serum carcinoembryonic antigen monitoring, and colonoscopy. The objective of this comprehensive review is to discuss different patterns of relapses observed in colorectal cancer patients, present diagnostic options, and summarize different strategies and recommendations of the posttreatment surveillance.