['The metabolic syndrome (MetS) increases the risk of cardiovascular disease morbidity and mortality. MetS is also associated with increases in the number of circulating white blood cells. Lymphocyte sub-population counts have also been implicated in cardiovascular disease; this analysis will examine whether or not they are associated with MetS.', 'Participants were 4255 Vietnam-era US veterans. From military service files, telephone interviews, and a medical examination, occupational, socio-demographic, and health data were collected. MetS was ascertained from: body mass index; fasting blood glucose or a diabetes medication; blood pressure or a diagnosis of hypertension; HDL cholesterol; and triglyceride levels. Circulating T, T4, T8 and B lymphocytes cell numbers were determined by flow cytometry.', 'In fully adjusted logistic regression analyses, high lymphocyte sub-population counts were associated with an increased risk of MetS: T cells, OR=2.68, 95%CI 1.99-3.61, p<.001; T4 cells, OR=2.37, 95%CI 1.78-3.15, p<.001; T8 cells, OR=1.79, 95%CI 1.43-2.24, p<.001; B cells, OR=1.82, 95%CI 1.51-2.19, p<.001. High lymphocyte sub-population numbers were also associated with an increased likelihood of possessing each of the MetS components, as well as the number of components possessed.'] Are lymphocyte sub-population cell counts associated with the metabolic syndrome and its components in the Vietnam Experience Study?