BACKGROUND Components of the metabolic syndrome are typically intercorrelated in epidemiologic studies and, when combined, predict type 2 diabetes and cardiovascular diseases. However, it remains unclear whether a single construct underlies the various components and which of the components are most closely associated with the underlying syndrome. Here, we use our confirmatory factor analytic model of the metabolic syndrome to examine the extent to which measures of ambulatory blood pressure, reflecting blood pressure variability throughout the day and night, may strengthen the association between blood pressure and the other components of the syndrome. METHODS Participants were a community sample of 358 men (248 with hypertension), ages 40-70, not receiving antihypertensive medications. Confirmatory factor analysis was employed to examine model fit and the strength of association between clinic and ambulatory blood pressure and the metabolic syndrome. RESULTS The blood pressure factor loaded significantly on the underlying metabolic syndrome but the strength of association was not as great (loading = 0.34, p < 0.01) as those observed for the obesity, insulin resistance and lipid factors. The factor loadings for the ambulatory measures (awake loading = 0.19; sleep loading = 0.16, p values < 0.01) were significant but smaller in magnitude than the loadings for clinic blood pressure. CONCLUSIONS Both clinic and ambulatory measures of blood pressure are significantly associated with the underlying metabolic syndrome using confirmatory factor analytic methods. However, the strength of association appears greater for the clinic measures relative to the ambulatory measures in this study.