Our objectives were to determine the prevalence and factors related to left ventricular hypertrophy (LVH) among older women for commonly used electrocardiographic criteria. LVH is a potent risk factor for cardiovascular disease, especially among women. However, its value has been limited, in part, by the use of different electrocardiographic criteria and the lack of a clearly defined standard for the general population. A total of 3,613 eligible women, aged 50 to 79 years, underwent medical history, physical measurements, and biochemical determinations and had behavioral factors recorded at baseline. Three LVH indexes were derived from computer measurement of the electrocardiogram: hypertrophied left ventricular mass > or =171.04 g (HLVM); Cornell voltage > or =2,200 microV; and Minnesota Code items. The prevalence of LVH ranged from <1% to 13% when stratified by age, ethnicity, and scoring technique. Baseline traits differed significantly for those meeting the LVH criteria. Predictors (p <0.01) of HLVM were age (odds ratio 0.66), height (odds ratio 1.47), waist/hip ratio (odds ratio 1.30), systolic blood pressure (odds ratio 1.18); low-density lipoprotein cholesterol (odds ratio 0.97), log insulin (odds ratio 2.10), dietary kilocalories (odds ratio 1.16), weekly energy expenditure (odds ratio 0.53), hypertension (odds ratio 1.61), current estrogen use (odds ratio 0.60), and current smoker (odds ratio 0.47). The presence of the metabolic syndrome was related to all LVH indexes, with odds ratios of 4.95, 2.24, and 2.35, respectively, for HLVM, Cornell voltage, and Minnesota Code. In conclusion, the prevalence of LVH varied by ethnicity and the electrocardiographic index used. However, the baseline traits, especially the factors associated with the metabolic syndrome, were consistently and strongly related to all LVH indexes, particularly HLVM. Intervention on these factors may provide strategies for reducing LVH, a strong independent risk factor for cardiovascular morbidity and mortality among women.