The aim of the present study was to evaluate the long-term outcome of a behavioural medicine rehabilitation programme and the outcome of its two main components, compared to a 'treatment-as-usual' control group. The study employed a 4 x 5 repeated-measures design with four groups and five assessment periods during a 3-year follow-up. The group studied consisted of blue-collar and service/care workers on sick leave, identified in a nationwide health insurance scheme in Sweden. After inclusion, the subjects were randomised to one of the four conditions: behaviour-oriented physiotherapy (PT), cognitive behavioural therapy (CBT), behavioural medicine rehabilitation consisting of PT+CBT (BM) and a 'treatment-as-usual' control group (CG). Outcome variables were sick leave, early retirement and health-related quality of life. A cost-effectiveness analysis, comparing the programmes, was made. The results showed, consistently, the full-time behavioural medicine programme being superior to the three other conditions. The strongest effect was found on females. Regarding sick leave, the mean difference in the per-protocol analysis between the BM programme and the control group was 201 days, thus reducing sick leave by about two-thirds of a working year. Rehabilitating women has a substantial impact on costs for production losses, whereas rehabilitating men seem to be effortless with no significant effect on either health or costs. In conclusion, a full-time behavioural medicine programme is a cost-effective method for improving health and increasing return to work in women working in blue-collar or service/care occupations and suffering from back/neck pain.