OBJECTIVE: Guidelines for the management of acute low back pain in primary care recommend early intervention to address psychosocial risk factors associated with long-term disability. We assessed the cost utility and cost effectiveness of a brief pain management program (BPM) targeting psychosocial factors compared with physical therapy (PT) for primary care patients with low back pain of <12 weeks' duration. METHODS: A total of 402 patients were randomly assigned to BPM or PT. We adopted a health care perspective, examining the direct health care costs of low back pain. Outcome measures were quality-adjusted life years (QALYs) and 12-month change scores on the Roland and Morris disability questionnaire. Resource use data related to back pain were collected at 12-month followup. Cost effectiveness was expressed as incremental ratios, with uncertainty assessed using cost-effectiveness planes and acceptability curves. RESULTS: There were no statistically significant differences in mean health care costs or outcomes between treatments. PT had marginally greater effectiveness at 12 months, albeit with greater health care costs (BPM 142 pounds, PT 195 pounds). The incremental cost-per-QALY ratio was 2,362 pounds. If the UK National Health Service were willing to pay 10,000 pound per additional QALY, there is only a 17% chance that BPM provides the best value for money. CONCLUSION: PT is a cost-effective primary care management strategy for low back pain. However, the absence of a clinically superior treatment program raises the possibility that BPM could provide an additional primary care approach, administered in fewer sessions, allowing patient and doctor preferences to be considered.