A prospective study was conducted to assess the value of routine haemoccult testing as an indicator of early luminal recurrence of colorectal cancer. One hundred patients (mean age 72 years) undergoing radical resection (70% Dukes' B and 30% Dukes' C) for colorectal carcinoma were asked to provide 3-monthly haemoccult tests to a special follow-up clinic for a minimum of 5 years. Positive tests underwent further investigation with barium enema and colonoscopy. Patient compliance was 84%. Positive tests were obtained in 14 asymptomatic individuals, five of whom proved to have anastomotic recurrence. Recurrence was also identified in a further patient despite a negative haemoccult test. Three patients with anastomotic recurrence were able to undergo further radical surgery; two were still alive over 5 years after detection of recurrent disease. Haemoccult screening appears to detect increased numbers of patients with luminal recurrence (7.2%) when compared to historical controls (2.1%). Larger studies will be needed to determine if this increased detection rate results in improved long-term survival.