Loco-regional recurrence in squamous cell carcinoma of the head and neck can occur at the site of the original primary tumour or in the marginal zone at its periphery. While nodal recurrence may occur in previously involved nodes or in uninvolved nodes within or outside the treatment volume. The exact site of failure was determined in 89 patients treated with radical radiotherapy for carcinoma of the head and neck. Of 73 patients who failed at the primary site 71 (97%) did so within the site of the original tumour; only two patients developed a marginal recurrence. Of the 30 (93%) patients with N1-3 disease who later showed failure in the lymph nodes, 28 (93%) did so at their original site of disease. These results support the view that when radiation fails it usually does so in the centre of the tumour. In order to improve our results we need to deal with radioresistance at the site of mass disease. Ways of approaching this include the combination of surgery with radiotherapy, the addition of a sensitiser or an increase in the dose to the tumour mass by boosting a 'mini' volume using conformal techniques.