The aim of this study was to assess the cost–utility of a practice-based osteopathy clinic for subacute spinal pain. A cost–utility analysis was performed alongside a pragmatic single-centre RCT in a primary-care osteopathy clinic accepting referrals from 14 neighbouring practices in North-West Wales, UK. Patients with back pain of 2–12 weeks’ duration were randomly allocated to treatment with osteopathy plus usual GP care or usual GP care alone. Costs were measured from an NHS perspective. All primary and secondary healthcare interventions recorded in GP notes were collected for the study period. Quality adjusted life year (QALY) gains were based on EQ-5D responses from patients in the trial, and then cost per QALY ratios. Osteopathy plus usual GP care was more effective but resulted in more healthcare costs than usual GP care alone. The point estimate of the incremental cost per QALY ratio was £3560 (80% CI £542–£77 100).