- OBJECTIVE: To conduct a systematic review of the rehabilitation literature of moderate to severe acquired brain injuries (ABI) from traumatic and non-traumatic causes. METHODS: A review of the literature was conducted for studies looking at interventions in ABI rehabilitation. The methodological quality of each study was determined using the Downs and Black scale for randomized controlled trials (RCTs) and non-RCTs as well as the Physiotherapy Evidence Database (PEDro) scale for RCTs only. RESULTS: Almost 14 000 references were screened from which 1312 abstracts were selected. A total of 303 articles were chosen for careful review of which 275 were found to be interventional studies but only 76 of these interventional studies were RCTs. From this, 5 levels of evidence were determined with 177 conclusions drawn; however of the 177 conclusions only 7 were supported by two or more RCTs and 41 were supported by one RCT. CONCLUSION: Only 28% of the interventional studies were RCTs. Over half of the 275 interventional studies were single group interventions, pointing to the need for studies of improved methodological quality into ABI rehabilitation.