We aimed to estimate temporal trends in the proportion of HIV diagnoses which could be characterized as recent infections in Australia for men who have sex with men (MSM), people who inject drugs (PWID), and heterosexual men and women using modified back-projection methodology based on data sources from HIV/AIDS Surveillance database. The proportion of HIV diagnoses among MSM that can be classified as recent infections increased in MSM, heterosexual men and women consistently. However, after initial increases during 1996-2000, the proportion of overall recent infections estimated among PWID declined by 50% in 2007 compared to 2000 (from 23 to 11%). These data suggest that late HIV diagnoses were more common among PWID compared to other groups. Ongoing prevention efforts need to be coupled with targeted testing and treatment efforts to increase the diagnosis of recent infection in PWID and reduce apparent inequities in access to screening.