Background Multidisciplinary rehabilitation is recommended to reduce sickness absence and disability in patients with subacute or chronic low back pain (LBP). This study aimed to investigate whether a 12-week coordinated work oriented multidisciplinary rehabilitation intervention was effective on return to work and number of days off work during one-year follow-up when compared to usual care. Methods This study is a randomized controlled trial comparing the effectiveness of a 12-week multidisciplinary vocational rehabilitation program in addition to usual treatment. 770 patients with LBP, who were sick-listed, or at risk of being sick-listed were included in the study. The primary outcome was number of days off work due to LBP. The secondary outcomes were disability, health-related quality of life, pain, psychological distress and fear avoidance behavior. Data were collected at baseline, at the end of treatment, and at 6- and 12-months follow-up. Analyses were carried out according to the "intention-to-treat" principles. Results A significant decrease in the number of patients who were on sick-leave was found in both groups at the end of treatment and at 6- and 12-months follow-up. Additionally, disability, pain, health related quality of life, psychological distress, and fear avoidance beliefs improved in both groups. No statistically significant differences were found between the groups on any of the outcomes. Conclusions The coordinated multidisciplinary intervention had no additional effect on sickness absence, disability, pain, or health related quality of life as compared with that of usual care.