This paper presents an analysis of frication of Australian English voiceless plosives in spontaneous speech. Group and individual patterns in the rate of frication of /p t k/ in the speech of eight male twins from Melbourne are analysed. /k/ was fricated most often (17.2%), then /p/ (11.6%), while /t/ was rarely fricated (0.9%). /p/ and /k/ exhibited extensive individual variation in frication behaviour even within twin pairs and proportions of fricated tokens were relatively consistent within-speaker across sessions. By contrast, since /t/ was very rarely fricated it showed little variation among speakers. Sociolinguistic patterning in the frication of voiceless plosives in Australian English is considered. Implications of these findings for the characterisation of individual speakers are discussed.