Objectives: To estimate the prevalence of the metabolic syndrome in hypertensive subjects, and to examine the frequency of the components of the metabolic syndrome. Research design and methods: The authors studied a descreiptive, cross-sectional, population-based sample of 1,274 hypertensive subjects aged 40-70 years in department of Cardiology - the Da Nang hospital (6/2011- 6/2012). We measured blood pressure, waist circumference, fasting glucose, triglycerids (TG) and HDL cholesterol (HDLc). The metabolic syndrome was defined by the National Cholesterol Education Program (NCEP) and the Adult Treatment Panel III (ATP III) criteria, and by NCEP ATP III ceiteria but using waist circumference criteria for Pacific Asian (NCEP ATP III-Pacific Asian). Result: 1,274 hypertensive subjects included 611 men (47.95 percent) and 663 women (52.05 percent) with mean age was 57.32 + or - 9.12. The prevalence of metabolic syndrome was 496 (38.93 percent) by NCEP ATP III definition and 666 (52.76 percent) by the NCEP ATP III-Pacific Asian definition. This prevalence was higher in women than men (p0.001). It was highest in men aged 40-50 years and in women 61-70 years. The frequency of the components of metabolic syndrome in hypertension subjects who had metabolic syndrome were in turn increased TG 446 (89.16 percent) low HOLc 340 (73.21 percent), high fasting glucose 208 (41.64 percent) and increased waist circumference 187 (36.22 percent). If using NCEP ATP III-Pacific Asia criteria, increased waist circumference was the second prevalent parameter 501 (77.04 percent) below increased TG 598 (85.78 percent). The prevalences of the combination types of components in metabolic syndrome also depended on diagnostic criteria, they were 70.24 percent (3 components), 24.98 percent (4 components), 7.89 percent (5 components) if using NCEP ATP III criteria and are 59.36 percent (3 components), 33.44 percent (4 components), 9.89 percent (5 components) with NCEP ATP III-Pacific Asian criteria. In three components group, hypertension-increased TG-increased waist circumference combination with NCEP ATP III criteria. Conclusions: The prevalence of metabolic syndrome was high in hypertension and it was higher in women than men. It was highest in men aged 40-50 years and in women aged 61-70 years. The prevalentcomponents were increased TG, low HDLc (NCEP ATP III) and increased TG, increased waist circumference (NCEP ATP III-pacific Asian). The prevalences of the combination types of componests in metabolic sundrome were 70.33 percent (3 components), 24.77 percent (4 components), 5.94 percent (5 components) if using NCEP ATP III criteria and are 59.45 percent (3 components), 33.24 percent (4 components), 9.67 percent (5 components) with NCEP ATP III-Pacific Asian criteria.