This prospective longitudinal clinical study evaluates the prognostic value of age in the therapy outcome of patients with chronic low back pain treated with a multidisciplinary therapy. Four hundred five patients with chronic low back pain for 3 months or longer and a corresponding sick leave for longer than 6 weeks underwent a 3-week standardized multidisciplinary therapy. Patients were assigned into three groups of age with comparable baseline values at T0. At the 6-month follow-up (T1) five different therapy outcomes were analysed and compared in the three groups: back-to-work status, generic health status (SF36), pain intensity, functional capacity, and satisfaction with the therapy. All three treatment groups improved significantly in all outcome criteria between T0 and T1 except of functional capacity, which did not improve in the older patients. In the total group, the back-to-work rate was 61.7%. At the final follow-up, there were significantly better results in terms of functional capacity and pain level in younger patients, whereas back-to-work rate and satisfaction with therapy did not show a significant difference between the groups analysed. According to the results of this study, older patients with chronic low back pain also derive significant benefit from a multidisciplinary treatment strategy, although in some outcome criteria results were inferior to those obtained in younger patients.