This paper investigated the prospective predictors of mental health after breast cancer diagnosis among mid-aged Australian women (initially aged 45-50 years). Two waves of data collected 2 years apart from a longitudinal population-based survey of 12,177 women identified a group of 63 women who reported onset of BC between T1 (T1) and Time 2 (T2). The measures of interest in the current analysis were the sub-scales of the SF-36, a standard self-report measure of health-related quality of life, and three demographic variables (having a partner, speaking English at home, and having paid employment). Multivariate regression analysis with T2 mental health as the outcome variable revealed that both T1 mental health and bodily pain contributed significantly to mental health at T2, with mental health being the greatest contributor. It was concluded that the experience of breast cancer is not damaging to mental health per se, but such a life stressor is likely to impact most on the mental health of women who already had less robust mental health. (Contains 2 tables.)