The aim a follow-up programme in patients with cancer is to detect relapse or metastases in an early asymptomatic stage. This is only useful if the diagnosis of recurrence has implications for treatment and if early treatment of recurrence leads to an improved prognosis. This is certainly the case for liver metastases of colon cancer. Surgical resection of localised liver metastases has a 25-30% 5-year survival. Early chemotherapy for non-resectable metastatic disease improves the survival and prolongs the symptom-free period in comparison with chemotherapy starting at the onset of symptoms. Follow-up for colorectal cancer should be offered to patients with the highest risk of recurrence and should consist of clinical examination, CEA monitoring, ultrasound of the liver, chest X-ray and periodic colonoscopy. Issues for further research are the determination of a follow-up programme with the highest sensitivity, the determination of the periodicity of follow-up, the search for prognostic factors for recurrence, cost issues and the final proof of a survival benefit in a large follow-up programme. CONCLUSIONS: Indirect evidence supports the need for a good follow-up programme for colorectal cancer focussing on the detection of liver metastases.