Our project is closely related to the previous study "Rehabilitation aftercare - a new credo for rehabilitation clinics"; the intensified aftercare-strategy was developed by an interdisciplinary group of health professionals and scientists for patients with chronic back pain. Main objective is the resumption and maintenance of regular physical activity in everyday life of pa-tients undergoing rehabilitation. The aim of our present study was to evaluate the long-term (24-month-follow-up) efficacy of the "New Credo" (inpatient medical rehabilitation+intensified aftercare=IG) as compared with usual care (inpatient medical rehabilitation=CG). We conducted a prospective controlled multicentre trial (IG: 3 clinics vs. CG: 3 clinics) with 4 points of measurement (T0: before and T1: after rehabilitation as well as T3: 12 and T4: 24 month after discharge). We enrolled rehabilitants with a primary diagnosis of chronic back pain (ICD-10: M51-54) who had given their consent. Exclusion criteria were mental and/or psychological impairments as well as surgery in the past 6 months. Primary Outcomes included restriction of social participation (IMET) and functional capacity (FFbH-R). Treatment effects were evaluated using analyses of variance and adjusting for differences between baseline -values; furthermore we calculated effect sizes (SMDInter, SMDIntra, ORs). Complete data were available for 123 IG-rehabilitants and 299 CG-participants (Completer-Analysis, response: 52%). Regarding restriction in functional capacity in everyday life (FFbH-R) multivariate analysis confirmed a treatment*time interaction, the appropriate effect-sizes showed no significant effects (SMDInter and SMDIntra). With respect to long-term effects 24 months after discharge no significant effects were found for social participation, however. With respect to secondary outcomes there are no significant differences between the groups (SMDInter, ORs); in fact rehabilitants of both groups showed similar effects (SMDIntra) in most cases. In summary our results doesn't confirm that the intensified aftercare-programme is able to improve longer-term effectiveness of inpatient orthopaedic rehabilitation up to 24 month.