The effectiveness of a behavioural treatment was investigated in patients with chronic tension headache. The treatment program consisted of progressive relaxation, EMG-biofeedback and cognitive methods. At the end of the treatment, as well as at a 6 months follow-up, the patients reported a marked decrease in headache intensity and duration. A qualitative analysis was performed with patients who did not show progress and with dropouts. It revealed several variables which could have impeded behavior change such as the variability of headache intensity, positive consequences of pain behavior, the attribution of pain to illness, frequenting general practitioners, medical specialists and paramedics, the expected negative consequences of re-employment, the investment in the treatment and activities towards self-management. Further research should reveal whether readjustment of these variables will increase treatment effectiveness.