The aim of this study was to examine the impact of age on the perceptions of mental and physical health in an Australian population. A cross-sectional study of the Queensland population was conducted via telephone interviews (n = 1165). The Short Form-12 Health Survey was used to measure the population’s perceived physical and mental health and additional demographic information was collected. Groups with participants who were aged 18–24, 25–34, 35–44, 45–54, 55–64, and > 65 years were compared. The results suggested that the participants’ perceptions of mental health gradually increased with age, as the 55–64 and > 65 years old age groups scored significantly higher than did the younger age groups. Conversely, the older participants scored significantly lower than the younger participants on the physical health scale. Further research is warranted to consider the factors that might influence the perceptions of mental health across the life span.