BACKGROUND: The aim of this study was to investigate the relationship of the prevalence and risk of the metabolic syndrome to body mass index (BMI) in Australian Aboriginal people. DESIGN: It was a cross-sectional, secondary analysis of data obtained from population-based screenings in Aboriginal communities in central and northern Australia (913 participants recruited between 1993 and 1997). RESULTS: Forty-one percent of men and 48% of women conformed to the National Cholesterol Education Program definition for the metabolic syndrome (chi2=3.72, P=0.054). The prevalence of low high-density lipoprotein-cholesterol was high in all BMI categories (89 and 95% in men and women, respectively). The prevalence of all other metabolic abnormalities increased linearly with BMI. CONCLUSION: The metabolic syndrome is highly prevalent in Aboriginal communities and is strongly associated with BMI. Low high-density lipoprotein-cholesterol was the predominant component of the metabolic syndrome across sex groups and BMI strata.