HIV-related risk perceptions and risk practices among gay men have changed over time. We revisited perceived HIV risk and engagement in anal intercourse with casual partners among HIV-negative gay men who participated in one of the Sydney Gay Community Periodic Surveys (GCPS). Perceived HIV risk was assessed by a range of anal intercourse practices combined with pre-specified casual partners' HIV status and viral load levels. Perceived HIV risk forms a potential hierarchy, broadly reflecting differences in the probability of HIV transmission through various anal intercourse practices. To a lesser extent, it also varies by casual partners' HIV status and viral load. Men who had unprotected anal intercourse with casual partners (UAIC) perceived lower HIV risk than those who used condoms consistently in the 6 months prior to survey. Recognising the complex associations between risk perceptions and risk practices helps to better address challenges arising from the 'Treatment as Prevention' (TasP).