ObjectivePrisoners complete suicide and self-harm more frequently than members of the community. Sex offenders have been found to be at greater risk of engaging in these behaviours. This study examines the characteristics, prevalence, and predictors of self-harm and suicide attempts among: sex offenders that only victimise children (ChildSOs); adults (AdultSOs); or both (age-crossover polymorphous; PolySOs).MethodsData from three waves (1996, 2001, 2009) of the New South Wales (NSW) Inmate Health Survey was linked to the State’s re-offending database to identify men with histories of sexual offending. The health surveys captured self-report data on self-harm and suicidality.ResultsNon-sexual violent offenders (15%) and AdultSOs (14%) had the highest rate of self-harm, significantly more than ChildSOs (11%), non-sexual non-violent offenders (10%), and PolySOs (0%). Several factors significantly predicted self-harm at the bivariate level for both ChildSOs and AdultSOs, with unique predictors for each group. At the multivariate level, manic-depression trended towards significance for ChildSOs and any mental health condition remained a significant predictor for AdultSOs who self-harmed relative to AdultSOs who had not (aOR = 11.989, 95%CI [1.14, 126.66]). Approximately 23% of AdultSOs, 22% of PolySOs, and 19% of ChildSOs reported a suicide attempt throughout their lifetime, whereas only 15% of non-sexual non-violent offenders reported an attempt. At the bivariate level, few factors were significant for ChildSOs while several factors were significant for AdultSOs. At the multivariate level, a diagnosis of depression and treatment with psychiatric medication trended towards being significant predictors of suicide attempts for ChildSOs. In contrast, treatment with psychiatric medication (aOR = 25.732, 95%CI [1.91, 347.19])] remained a significant predictor for AdultSOs who attempted suicide relative to AdultSOs who had not, as well as historical psychiatric hospitalisation (aOR = 6.818, 95%CI [1.04, 44.82]) and self-harm (aOR = 5.825, 95%CI [1.31, 25.99]).ConclusionSex offenders are at significantly higher risk of attempting and completing suicide relative to non-sexual non-violent offenders and warrant special attention. The prevalence rates and predictors of self-harm and suicidality suggest differences between sex offender subgroups may exist. These hold implications for the criminal justice and public health systems for addressing needs and identifying those most at risk of self-harm and suicide.