BACKGROUND: Adjuvant chemotherapy (5-fluorouracil, levamisole) is now standard practice in the treatment of Dukes' B and C coloretal carcinoma (CRC), and this has increased the financial burden on health care systems world-wide. PATIENTS AND METHODS: Between 1993 and 1996, 95 patients in northern Norway were included in a national randomised CRC study, and assigned to surgery plus adjuvant chemotherapy or surgery alone. In April 1996, 94 of the patients were evaluable and 82 were still alive. The total treatment costs (hospital stay, surgery, chemotherapy, administrative and travelling costs) were calculated. A questionnaire was mailed to all survivors for assessment of the quality of their lives (QoL) (EuroQol questionnaire, a simple QoL-scale, global QoL-measure of the EORTC QLQ-C30), and 62 of them (76%) responded. RESULTS: Adjuvant chemotherapy in Dukes' B and C CRC raised the total treatment costs by 3,369 pounds. The median QoL was 0.83 (0-1 scale) in both arms. Employing a 5% discount rate and an improved survival of adjuvant therapy ranging from 5% to 15%, we calculated the cost of one gained quality-adjusted life-year (QALY) to be between 4,800 pounds and 16,800 pounds. CONCLUSION: Using a cut-off point level of 20,000 pounds per QALY, adjuvant chemotherapy in CRC appears to be cost-effective only when the improvement in 5-year survival is > or = 5%. Adjuvant chemotherapy does not affect short-term QoL.