Purpose: The quality of reports of randomized trials of physiotherapy interventions varies by year of publication, language of publication and whether the intervention being assessed is a type of electrotherapy. Whether it also varies by subdiscipline of physiotherapy has not yet been systematically investigated. The purpose of this study was to determine whether the quality of trial reports varies according to the subdiscipline of physiotherapy being evaluated. Methods: Reports of physiotherapy trials were identified using the Physiotherapy Evidence Database (PEDro). Quality of the trial report was evaluated using the PEDro scale (total PEDro score and 11 individual PEDro scale items). Multiple linear and logistic regressions were used to predict the quality of trial reports, with subdisciplines, time since publication, language of publication, and evaluation of electrotherapy as independent variables in the model. Results: Total PEDro scores are higher when trial reports are more recent; are published in English; investigate electrotherapy; and are in the subdisciplines of musculoskeletal, neurology, cardiopulmonary, gerontology, continence and women's health, orthopaedics, or paediatrics. Trials in the subdisciplines of ergonomics and occupational health, oncology, and sports are associated with lower total PEDro scores. The musculoskeletal subdiscipline had a positive association with six of the PEDro scale items, more than any other subdiscipline. Conclusions: There is scope to improve the quality of the conduct and reporting of randomized trials across all the physiotherapy subdisciplines. This study provides specific information about how each physiotherapy subdiscipline can improve trial quality.