We found no evidence about the effectiveness of an outpatient physiotherapy service without regard for the particular treatment method used. Outpatient physiotherapy includes a heterogeneous group of interventions. Although appraisal of each intervention is beyond the scope of this report, a recent high quality review has examined effectiveness of many specific interventions among people with low back pain. Evidence suggests that services which include advice to stay active during acute back pain and which provide exercise therapy for chronic back pain are more likely to be effective. The effectiveness of services that emphasise interventions such as massage, manipulation, shortwave diathermy, ultrasound, heat, ice packs or lumbar supports is more uncertain. However, effectiveness of a service as a whole is likely to depend on the package of interventions included, which should be clearly defined. The present review suggests that it is difficult or impossible to draw general conclusions about outpatient physiotherapy as a treatment strategy independently of the interventions included within a particular service. Decisions to provide a physiotherapy service for back pain must, therefore, pay close attention to the treatment modalities and protocols employed.