This study analyzes the results of a follow-up policy in colorectal cancer at our institution and evaluates the possible benefit provided by each test performed. Six hundred nineteen patients who had radical surgery and adjuvant treatment for colorectal cancer were followed up with a protocol that included carcinoembryonic antigen testing and clinical examination every three months for the first two years, every four months in the third year, and every six months in the fourth and fifth years. Chest X-ray and colonoscopy were performed yearly for five years and abdominal ultrasound was done every six months for the first three years and yearly afterward. Abdominopelvic computerized tomography was performed yearly for the first two years in cases with rectal cancer. If relapse was detected, all operable cases underwent surgery if possible. Between 1993 and 1999, 619 patients were followed-up. Mean follow-up was 66.9 months. Two hundred eight relapses were detected, 83.6 percent in the first three years and 73 (35.1 percent) underwent surgical resection. Carcinoembryonic antigen testing detected 44.2 percent of recurrences and 31.9 percent of them were operated on. Imaging techniques detected a lower percentage of recurrences (18.7 percent) but were more often resectable: 52 percent and 60 percent of the recurrences detected by computerized tomography and chest X-ray, respectively, underwent surgery. Median overall survival of patients with resected relapse was 62 months, significantly higher than those who were not operable (12.4 months). Imaging techniques in the surveillance of resected colorectal cancer contribute to early detection of relapse with a high proportion of operable metastatic disease.