The "Back-Pain Institute" at Sundsvall offers an advanced rehabilitation program to people with long-standing back pain. This program has been evaluated in a controlled prospective study. Data were gathered from questionnaires mailed on three occasions, from the sick insurance office and from the bureau of employment. The effects of the Institute's course on the vocational situation were small. The only significant difference between the experimental group and the control group was in the level of income. Significantly more persons in the experimental group had begun to train their back and significantly more individuals in the experimental group believed that by using the correct working technique they could prevent back pain. No significant changes were found with regard to the subjective feeling of pain.