Australia's prisoners have high rates of mental health issues. In 2010, 31 percent of prison entrants reported having ever been told that they had a mental health illness; and 16 percent of prison entrants reported that they were currently taking medication for a mental illness. Upon entry to prison, almost 20 percent of prison entrants were referred to the prison mental health services for observation and further assessment. Almost 1 in 10 prisoners visited the clinic for a psychological or mental health issue; and 1 in 5 prisoners in custody were taking medication for a mental illness. Prison entrants reported previously engaging in various risky health behaviors, such as smoking tobacco, drinking alcohol at extreme levels, and using illicit drugs. Four in five prison entrants reported being a current smoker; and three in four reported being a daily smoker. Just over half of prison entrants reported drinking alcohol at levels that placed them at risk of alcohol-related harm. Two-thirds of prison entrants reported illicit drug use in the previous 12 months. Aboriginal and Torres Strait Islander prison entrants were significantly over-represented in the entrant's sample, with 43 percent being Indigenous, compared with 2.5 percent of the general population. Indigenous prison entrants reported poorer health behaviors than non-Indigenous prison entrants and were more likely to be current smokers and to have consumed alcohol at levels considered to place them at risk for alcohol-related harm in the previous 12 months. Most data for this report came from the National Prisoner Health Census, which was conducted during October and November 2010 in 44 of the 45 public and private prisons.