One-hundred and six consecutive patients were included in a prospective study of intensive monitoring after radical resection for colorectal cancer, 54 being randomized into a conventional follow-up group (Group I) and 52 into an intensified follow-up group (Group II). After a median follow-up of 2 years the overall rate of detection recurrence in Group I was 24% (13/54) and in Group II 25% (13/52). The recurrence rates among those followed up for at least 2 years were 36% (10/28) and 30% (9/30), respectively. Of the recurrences in Group I, one was local, five regional and six distant, and the corresponding figures in Group II were three, four and five. One radical extirpation of a local perineal recurrence has been performed in Group I, whereas two intestinal reresections for local anastomotic recurrences and two hepatic resections for solitary hepatic metastases have been performed in Group II. Mortality to date is 13% (7/54) in Group I and 8% (4/52) in Group II. Two adenomatous polyps have been removed from the colon in Group I during endoscopic surveillance and seven in Group II. These preliminary results encourage us to continue the trial up to 5 years after primary surgery.