OBJECTIVE: To assess whether a diagnosis of the metabolic syndrome (MetS) improves the prediction of cardiovascular disease or total mortality beyond that already provided by conventional risk factors. DESIGN AND SETTING: A longitudinal cohort study conducted in Dubbo, New South Wales. PARTICIPANTS: 2805 men and women aged 60 years and older living in the community, first assessed in 1988-1989 and followed for 16 years. MAIN OUTCOME MEASURES: Coronary heart disease (CHD) events, ischaemic stroke events, and total mortality. RESULTS: MetS was present in 31% of men and 34% of women. Crude CHD, ischaemic stroke, and total mortality rates were higher in the presence of MetS in men and women. In proportional hazards models that included conventional risk factors, but excluded variables used to define the presence of MetS, MetS was a significant predictor of CHD, stroke and total mortality. In men, the respective hazard ratios were 1.64 (95% CI, 1.37-1.96), 1.31 (95% CI, 0.97-1.77), and 1.53 (95% CI, 1.30-1.79). In women, the respective hazard ratios were 1.70 (95% CI, 1.43-2.02), 1.37 (95% CI, 1.04-1.82), and 1.35 (95% CI, 1.15-1.59). The use of MetS variables on an ordinal scale produced broadly similar conclusions. CONCLUSIONS: A diagnosis of MetS provides additional prediction of CHD events, stroke events, and total mortality beyond that provided by other conventional risk factors.