88 patients, aged 19 to 59, with acute mechanical low back pain (AM-LBP) were randomized to receive either the hospital based chiropractic comprehensive clinical guidelines-based care or family physician-directed arbitrary usual care (control). The primary outcome measure of Roland-Morris Disability Questionnaire (RDQ) scores at 16 weeks were found improved (p=0.003) with structured chiropractor care in comparison with the usual family physician care. Also, the treatment group showed improvements in disability, bodily pain, and physical function at 24 weeks follow up (p=0.004).