Introduction and aimsPrison entrants commonly have a history of problematic alcohol and other drug (AoD) use. Aboriginal and Torres Strait Islander (Indigenous) Australians are vastly overrepresented in Australian prisons with an incarceration rate 16 times that of non-Indigenous Australians. Relatively little attention has been given to the patterns of AoD use among prison entrants and we hypothesise that they may differ between Indigenous and non-Indigenous entrants. The aim of this paper is to compare the prior AoD use among Indigenous and non-Indigenous prison entrants and identify the implications for AoD treatment provision within prisons.Design and methodCross-sectional random sample of 200 men recently received into New South Wales (NSW) criminal justice system.ResultsDuring the 12 months prior to imprisonment, 106 prison entrants consumed alcohol at levels at which an intervention is recommended. Additionally during the four weeks prior to prison, 94 inmates had used illicit drugs daily. There was some overlap between these two groups; however, heroin users were less likely to consume alcohol at harmful levels. Relative to non-Indigenous entrants, Indigenous entrants prior to imprisonment used more cannabis but less amphetamine on a daily basis. There were no other significant differences between the alcohol or drug use of Indigenous and non-Indigenous prison entrants.Discussion and conclusionBoth Indigenous and non-Indigenous men entering prison have a history of high levels of AoD use but a slightly different treatment focus may be required for Indigenous inmates.