To evaluate, through two studies, the factor structure, inter-rater agreement, and test–retest and inter-rater reliability of the Sport Injury Rehabilitation Adherence Scale (SIRAS).Repeated measures design in both Study 1 (video evaluation) and Study 2 (clinical evaluation).University department (Study 1) and outpatient physiotherapy department (Study 2).Sixty physiotherapists and physiotherapy students in Study 1 and 45 patients undergoing physiotherapy treatment for a musculoskeletal injury in Study 2.In Study 1, participants rated the adherence of a simulated videotaped patient demonstrating high, moderate and low adherence during rehabilitation. In Study 2, two physiotherapists rated the adherence of patients at two consecutive rehabilitation sessions.The SIRAS.In Study 1, principal components analysis confirmed a single factor for the SIRAS, and inter-rater agreement values ranged from 0.87 to 0.93. In Study 2, inter-rater and test–retest reliability coefficients ranged from 0.76 [95% confidence interval (CI) 0.54 to 0.83] to 0.89 (95% CI 0.79 to 0.95), and from 0.63 (95% CI 0.36–0.82) to 0.76 (95% CI 0.55–0.88), respectively.The SIRAS is a reliable measure with high inter-rater agreement when used to evaluate clinic-based adherence to physiotherapy rehabilitation for musculoskeletal injury.