BackgroundAboriginal alcohol and other drug residential rehabilitation (residential rehabilitation) services have been providing treatment in Australia of over 50 years. However, there are no studies in Australia or internationally that document characteristics of clients attending Indigenous residential rehabilitation services worldwide. This is the first multi-site paper to describe key client characteristics of six Indigenous (hereafter Aboriginal Australians as the term recommended by the Aboriginal Health and Medical Research Council of New South Wales) residential rehabilitation services in Australia.MethodsAll recorded client admissions between 1 January 2011 to 31 December 2016 were considered from six operating services in the Australian state of New South Wales. Data collected were classified into categories based on demographics, treatment utilisation, substance use, mental health and quality of life characteristics. Means, median and percentages were calculated (where appropriate).ResultsThere were 2645 admissions across the six services in the study period, with an average of 440 admissions per year across all services. Participants were aged between 26 to 35 years, with fewest participants aged 46 +. Program length ranged from 12 to 52 weeks (mean of 12 weeks). The completion rates and length of stay for each service ranged from less than two to more than 12 weeks. The principal drug of choice was alcohol and amphetamines in half of the services. Not all services used them, but a range of tools were used to measure treatment, substance use and mental health or quality of life outcomes.ConclusionThis study is the first internationally to describe the key features of multiple Aboriginal residential rehabilitation services. The variation in tools used to collect client data made it difficult to compare client characteristics across services. Future research could explore predictors of treatment completion, identify opportunities for standardisation in client assessments and validate cultural approaches of care. These efforts would need to be guided by Aboriginal leadership in each service.