Ergonomic interventions (physical and organisational) areused to prevent or reduce low back pain (LBP) and neck pain among workers. We conducted a systematic review of randomised controlled trials (RCTs) on the effectiveness of ergonomic interventions. A total of 10 RCTs met the inclusion criteria. There was low to moderate quality evidence that physical and organisational ergonomic interventions were not more effective than no ergonomic intervention on short and long term LBP and neck pain incidence/prevalence, and short and long term LBP intensity. There was low quality evidence that a physical ergonomic intervention was significantly more effective for reducing neck pain intensity in the short term (ie, curved or flat seat pan chair) and the long term (ie, arm board) than no ergonomic intervention. The limited number of RCTs included make it difficult to answer our broad research question and the results should be interpreted with care. This review, however, provides a solid overview of the high quality epidemiological evidence on the (usually lack of) effectiveness of ergonomic interventions on LBP and neck pain.