Objectives: To describe the concentrations of serum ferritin among Australian adults by age and sex. Further, the relationships of various social, lifestyle and health factors with serum ferritin concentrations were explored. Design: A total of 1634 adults aged >25 years from six randomly selected urban centres in Queensland, Australia participated in the study that was conducted between October and December 2000. Results: Prevalence of depleted iron stores, based on low serum ferritin concentration, was 10.6% among females aged <50 years, 2.8% among females aged >50 years and virtually nil among males. In contrast, 16% of the males and 20% of the females aged >50 years had elevated serum ferritin concentrations. Significantly higher serum ferritin concentrations were found among females of both age groups who consumed alcohol at a rate of >60 drinks/month, and females aged <50 years who were obese. Lower serum ferritin concentrations were found only among females aged <50 years, with higher education attainment. In multivariable analysis, only the association between higher serum ferritin and obesity was consistent across age-sex groups and statistically significant. Conclusion: Iron deficiency may be a problem among Australian females of reproductive age. Further research is needed to identify the determinants of low iron concentrations in younger females and elevated concentrations of serum ferritin in males and older females in order to develop preventive measures.