Background: Detained asylum seekers are at increased risk of self-harm, and the type of detention in which they are held may further exacerbate this risk. In Australia, there are four types of closed (or held) immigration detention for people seeking asylum, with varying levels of security and supports: Immigration Detention Centres [IDCs], Immigration Transit Accommodation [ITAs], Immigration Residential Housing [IRH], and Alternative Places of Detention [APODs]. The objective of this study was to examine the variation in the incidence and method(s) of selfharm among asylum seekers in Australian onshore immigration detention, according to the type of detention in which they are held. Methods: We obtained data on all self-harm incidents reported among asylum seekers in Australian onshore immigration detention according to held detention type, as well as individual facility, between 1 August 2014 and 31 July 2015, by Freedom of Information. We calculated self-harm episode rates per 1000 asylum seekers using the average population figures for held detention type, as well as for each individual facility comprising the main types of held detention. Method(s) used to self-harm was also extracted for the main sub-populations. Results: The study included 560 episodes of self-harm. Individual facility rates of self-harm ranged from 91 per 1000 asylum seekers (95% CI 72-110) in Yongah Hill IDC to 533 per 1000 asylum seekers (95% CI 487-578) in Perth IDC. On average, calculated self-harm episode rates were highest among asylum seekers in: Immigration Transit Accommodation facilities, 452/1000 (95% CI 410-493); Alternative Places of Detention, 265/1000 (95% CI 233-296); and Immigration Detention Centres, 225/1000 (95% CI 195-254). The most frequently reported methods of self-harm across the main types of held detention were: cutting (35.2%), self-battery (34.8%), and attempted hanging (11.1%). Conclusions: Self-harm rates for asylum seekers in all types of closed immigration detention were many times higher than rates found in the general population. Average rates were not lower in facilities with lower security features.