A molecular variant of the angiotensinogen gene with threonine instead of methionine at position 235 (ie, with M235T polymorphism) has been shown to be associated with essential hypertension in Caucasian populations. The purpose of the present study was to assess whether the M235T polymorphism was associated with essential hypertension in the Japanese population. The study population consisted of 347 subjects selected in our outpatient clinic. The clinical data included in the analyses were sex, age, body mass index, cholesterol level, genotype of the angiotensinogen gene, genotype of the angiotensin-converting enzyme gene, and systolic and diastolic blood pressure. Multiple regression analysis revealed that only body mass index was a predictor of both diastolic and systolic blood pressure in these 347 subjects, but the genotype of the angiotensinogen gene was identified as a predictor of both diastolic and systolic blood pressure in a subpopulation less than 50 years of age. However, in a subpopulation more than 50 years of age, body mass index was the only predictor of both systolic and diastolic blood pressure. Of the 347 subjects, 189 had a technically excellent echocardiogram at the initial observation period. Multiple regression analysis revealed that sex, body mass index, diastolic blood pressure, and genotype of the angiotensin-converting enzyme gene were predictors of left ventricular mass. Although subjects with the TT angiotensinogen genotype had significantly greater left ventricular mass than those with either the TM or the MM genotype, the effects of the genotype of the angiotensinogen gene on left ventricular mass were mainly due to effects on blood pressure.