Background. The working alliance, or collaborative bond, between client and psychotherapist has been found to be related to outcome in psychotherapy. Purpose. The purpose of this study was to investigate whether the working alliance is related to outcome in physical rehabilitation settings. Data Sources. A sensitive search of 6 databases identified a total of 1,600 titles. Study Selection. Prospective studies of patients undergoing physical rehabilitation were selected for this systematic review. Data Extraction. For each included study, descriptive data regarding participants, interventions, and measures of alliance and outcome - as well as correlation data for alliance and outcomes - were extracted. Data Synthesis. Thirteen studies including patients with brain injury, musculoskeletal conditions, cardiac conditions, or multiple pathologies were retrieved. Various outcomes were measured, including pain, disability, quality of life, depression, adherence, and satisfaction with treatment. The alliance was most commonly measured with the Working Alliance Inventory, which was rated by both patient and therapist during the third or fourth treatment session. The results indicate that the alliance is positively associated with: (1) treatment adherence in patients with brain injury and patients with multiple pathologies seeking physical therapy, (2) depressive symptoms in patients with cardiac conditions and those with brain injury, (3) treatment satisfaction in patients with musculoskeletal conditions, and (4) physical function in geriatric patients and those with chronic low back pain. Limitations. Among homogenous studies, there were insufficient reported data to allow pooling of results. Conclusions. From this review, the alliance between therapist and patient appears to have a positive effect on treatment outcome in physical rehabilitation settings; however, more research is needed to determine the strength of this association.