Objective: To assess whether psychological distress has changed in the Australian population. Method: Data were obtained from national household surveys of 1964 Australian adults in 1995 and 3507 in 2003–2004. Psychological distress was measured using the 4-NS, which asks about symptoms of depression, anxiety, irritability and nervousness in the past month. The data were analysed by gender and by age group, from 20–24 years to 70–74 years. Results: Psychological distress was found to have increased in men aged 20–29 years. This change was observed even when the same cohorts were compared. No change was found in women or in other male age groups. Conclusions: These data show the need for routine population monitoring of mental health to determine subgroups requiring priority action.