A systematic review of randomised clinical trials was conducted to investigate the efficacy of McKenzie therapy in the treatment of spinal pain. Databases searched included DARE, CINAHL, CENTRAL, EMBASE, MEDLINE and PEDro. To be eligible for inclusion trials had to provide treatment according to McKenzie principles and report on one of the following outcomes: pain, disability, quality of life, work status, global perceived effect, medication use, health care contacts, or recurrence. Six trials were found to be eligible, all comparing McKenzie therapy to a comparison treatment. These included NSAIDS, educational booklet, back massage and back care advice, strength training, and spinal mobilisation and general exercises. The data from five lumbar trials were pooled at short term (less than three months) and from three at intermediate (3-12 months) follow-up. At short term follow-up the McKenzie therapy provided a mean 8.6 point greater pain reduction on a 0 to 100 point scale (95% CI 3.5 to 13.7) and a 5.4 point greater reduction in disability on a 0 to 100 point scale (95% CI 2.4 to 8.4) than comparison. At intermediate follow-up, relative risk of work absence was 0.81 (0.46 to 1.44) favouring McKenzie, however the comparison treatments provided a 1.2 point greater disability reduction (95% CI -2.0 to 4.5). In the one cervical trial, McKenzie therapy provided similar benefits to an exercise program. The results of this review show that for low back pain patients McKenzie therapy does result in a greater decrease in pain and disability in the short term than other standard therapies. Making a firm conclusion on low back pain treatment effectiveness is difficult because there are insufficient data on long term effects on outcomes other than pain and disability, and no trial has yet compared McKenzie to placebo or no treatment. There are also insufficient data available on neck pain patients.