In a pilot study we treated 19 patients suffering from recurrent or locally advanced inoperable colorectal cancer, with concurrent hypofractionated radiotherapy (4-5 Gy/fraction, 2 fractions per week) and 5-fluorouracil bolus, 1 hour before RT at doses of 300 mg/m2. For 16 patients treated with radical intent the Normalised Total Dose for alpha/beta = 10 Gy ranged between 56-74 Gy (median 62 Gy). The schedule used was very well tolerated. Moderate grade II haematological toxicity was observed in 11% of cases and diarrhoea grade II/III resulting in 2-4 weeks treatment delay was observed in 26% of cases. One case with bowel perforation and one with painful subcutaneous fibrosis was observed during 12-27 months of follow-up. Out of 16 patients treated with radical intent 4 (25%) showed complete response and the overall response rate was 56% (9/16). The one-year symptom-free survival was obtained in 11/16 (69%) radically treated patients. It is concluded that hypofractionated radiochemotherapy with 5-fluorouracil for recurrent or locally advanced colorectal cancer is an effective regimen and has acceptable acute and late toxicity. Further investigation is required.