351 patients on sick leave for 3 to 16 weeks due to low back pain were randomized to receive a brief hospital-based intervention or a multidisciplinary intervention. The results of the study indicate that the patients that underwent a brief hospital-based intervention required significantly fewer sick leave weeks than the patients that underwent the multidisciplinary intervention during the first year follow-up. The difference became insignificant by the second year follow-up. Work related autonomy and security modified the effects of the interventions on return to work rates. No significant differences in return to work rates, return to work status, and sick leave relapse were found.