Chronic diseases of the musculoskeletal system rank first as causes of early retirement in Germany. Therefore orthopaedic rehabilitation has to identify patients with work-related problems and to promote return to work through differential treatment and vocational counselling. In the framework of the IopKo-Project such measures were developed and evaluated. These measures encompass: (1) an intensive and multiprofessional diagnostic pathway which allows early detection and treatment of mental disorders and job related problems; (2) homogeneous treatment groups based on multiprofessional diagnostics; (3) differential treatments, among these a multidisciplinary programme for patients with chronic low back pain or high risk of chronification (Rückenfit); (4) interactive training modules which mediate principles of performance and disability expertise, the legal bases of retirement pensioning, and measures to support occupational rehabilitation; and (5) a work hardening training programme. To evaluate the effects of these measures in comparison to a control group with usual care, a prospective longitudinal study was conducted. A total of 307 patients were assigned to the multidisciplinary in-patient treatment programme, whereas 176 patients in the control group had a standard rehabilitation programme. The results show positive moderate and strong effects in the intervention group concerning function, pain, psychic strains as well as the number of sick days and return to work rates 10 months after discharge. The effects in the intervention group exceeded the effects achieved in the control group. PATIENTS WITH HIGH RISK OF CHRONIFICATION: Beside the full sample, a subgroup of patients with chronic pain or high risk of chronification was analyzed, who had received a multidisciplinary functional restoration treatment. Also for this subgroup we found moderate and strong effects of treatment for function, psychic strains and sick days superior to those in the control group. By this study we were able to show that orthopedic rehabilitation in a multimodal and multidisciplinary setting with a focus on activating and motivating therapy can have sustainable positive effects on pain, function and psychic well-being as well as on economic parameters. We interpret these persistent and superior effects in the treatment group (1) as a result of multiprofessional diagnosis and assignment which helps to subdivide the inhomogeneous group of patients with unspecific back pain into more homogeneous and thus more effective subgroups, (2) as a result of increased motivation by closed treatment groups, (3) as a result of intense and multilevel counselling of work related problems, (4) as a result of work hardening modules, and (5) as a result of direct and efficient treatment of psychic strains. The results also demonstrate the significance of inpatient rehabilitation, which will be efficient if differential treatment - adequate to the problems of the patient - is offered.