Objective. To update the evidence on the effectiveness of lumbar supports, education and exercise in the primary prevention of low back pain at the workplace. Methods. A computerized search for controlled clinical trials published between 1997 and 2002 was conducted, and the methodological quality of the studies was assessed using a criteria list. The available evidence was graded with a rating system for the level of evidence. Effect sizes of individual studies were combined if the studies were sufficiently similar. Results. Five new papers were identified for the update. These trials were added to the previously available trials (n = 11). The methodological quality of most studies was low. Since three of four RCTs on lumbar supports reported no effect, there is no evidence for the effectiveness of lumbar supports. No evidence for education could be found either, since all six RCTs showed negative results. The four RCTs on exercise consistently reported a positive effect, indicating limited evidence for the effectiveness of exercise. Conclusion. There is no evidence for the effectiveness of lumbar supports or education in the primary prevention of low back pain at the workplace. There is limited evidence for the efficacy of exercise, and the effect that can be obtained is moderate. There is still a need for methodologically sound studies and studies on the cost-effectiveness of exercise. Also the possible effect of lumbar supports in the treatment of back pain needs further investigation. © Society of Occupational Medicine 2004; all rights reserved.