A prospective survey of the outcome following lumbar spine surgery was carried out during a period of six months. Of a consecutive series of 144 patients 130 cases (90%) could be evaluated. Postoperative follow-up was for six months. A test of psychological vulnerability was included with the preoperative data. Outcome was determined as unsatisfactory in case of re-operation (9%) before follow-up or if pain persisted unchanged or became worse (30%). Psychological vulnerability was significantly associated with poor outcome irrespective of age, sex, pre-operative somatic health, and surgical findings. The relative risk ratio of persisting pain attributable to psychological vulnerability was 1.8. The finding support the contention that psychogenic factors independently and significantly contribute to the multiple factor interaction that determines short-term outcome. The social consequences were strongly associated with psychological vulnerability. Among patients pre-operatively on sick-leave the relative risk ratio of unemployment attributable to psychological vulnerability was 6.0.