A systematic review of randomised controlled trials was undertaken to evaluate the effectiveness of workplace interventions to prevent low back pain. Potential trials were located by a computerised search supplemented with citation tracking. The methodological quality of the trials was assessed on 11 criteria and the level of evidence for each intervention was determined, based upon the amount, consistency and quality of evidence from the trials. The review located 13 trials that were generally of moderate quality. The trials suggest that work place exercise is effective, braces and education are ineffective, and workplace modification plus education is of unknown value in preventing low back pain.