We have assessed the influence of somatisation on the outcome of treatment in 81 patients with chronic low back pain. All, irrespective of whether treatment was surgical or conservative, had a significantly better (p < 0.001) health-related quality of life at follow-up on all but one scale of the SF-36. Lower health-related quality of life at follow-up correlated significantly with a higher tendency to somatise before treatment and at follow-up. A logistic regression analysis yielded two factors which predicted the outcome; somatisation (p < 0.001) and 'doctor shopping' (the number of physicians consulted before the present inpatient treatment, p < 0.001). These factors accurately distinguished between patients with good and those with poor outcomes in 82%. Patients with somatisation and 'doctor shopping' were at a higher risk for a poor outcome. The results show the relevance of somatisation in the outcome of treatment in patients with low back pain.