This study examined the increase in the rate of suicide by hanging and an apparently simultaneous decrease in the rate of suicide by firearm as hypothetical evidence that Australian males have substituted one method of suicide for another. Trends in hanging and firearm suicide rates were examined from 1975 to 1998 for all Australian males and from 1971 to 1998 for a subset of Australian male youth, as well as a group of Australian males aged over 64 years at the time of their death. When the firearm suicide rate for Australian males declined the hanging rate increased simultaneously, with no statistical difference in the rate of change of the two methods. A similar pattern of simultaneous divergence in hanging and firearm suicide rates of a 15- to 24-year-old subgroup occurred at a not dissimilar rate over a longer time period. Rates of suicide by hanging were found to have begun increasing prior to the decline in firearm suicide. The declining rate of firearm suicide in the 15- to 24-year-old subgroup coincided with an increase in the overall suicide rate. Relationships between trends in hanging and firearm suicide differed between states and between urban and non-urban areas within Queensland, with the firearm suicide rate falling more rapidly in urban areas, especially following the introductions of restrictions to weapon purchases. Individual suicide method choice may be related to independent changes in the social acceptability of each method, as well as to an increasing prevalence of suicide in younger males, who are more likely to use the hanging method. The functioning and effect of social acceptability remains unclear, however. Intervention and prevention strategies should focus on challenging the social acceptability of hanging, especially among males aged 15 to 24 years.