Background: The purpose of this systematic review was to determine the effectiveness and implementation of advanced allied health assistant roles. Methods: A systematic search of seven databases and Google Scholar was conducted to identify studies published in English peer-reviewed journals from 2003 to 2013 and reporting on the effectiveness and implementation of advanced allied health assistant (A/AHA) roles. Reference lists were also screened to identify additional studies, and the authors' personal collections of studies were searched. Studies were allocated to the National Health and Medical Research Council hierarchy of evidence, and appraisal of higher-level studies (III-1 and above) conducted using the Centre for Evidence Based Medicine Systematic Review Critical Appraisal Sheet for included systematic reviews or the PEDro scale for level II and III-1 studies. Data regarding country, A/AHA title, disciplines, competencies, tasks, level of autonomy, clients, training, and issues regarding the implementation of these roles were extracted, as were outcomes used and key findings for studies investigating their effectiveness. Results: Fifty-three studies were included, and most because they reported background information rather than investigating A/AHA roles, this representing low-level information. A/AHAs work in a range of disciplines, with a variety of client groups, and in a number of different settings. Little was reported regarding the training available for A/AHAs. Four studies investigated the effectiveness of these roles, finding that they were generally well accepted by clients, and provided more therapy time. Issues in integrating these new roles into existing health systems were also reported. Conclusion: A/AHA roles are being implemented in a range of settings, and appear to be effective in terms of process measures and stakeholder perceptions. Few studies have investigated these roles, indicating a need for research to be conducted in this area to enable policy-makers to consider the value of these positions and how they can best be utilized.