To evaluate the influence of proteinuria on the development of hypertension in normotensive screened subjects. We studied 4,428 normotensive subjects without heart disease (2888 men, 1540 women, age 19-89 years) who were participants in a 1-day health evaluation in both 1997 and 2000. The 3-year frequency of developing hypertension was 6.0% in subjects without proteinuria, and 13.5% in subjects with proteinuria. The odds ratio for developing hypertension by age (year) increased approximately 1.6%. Obesity was associated with an approximately 40% increased risk of hypertension; proteinuria increased the risk of hypertension 2-fold. Proteinuria was a significant predictor of developing hypertension. Age, obesity, and initial blood pressure level also contributed to the development of hypertension. In conclusion, proteinuria is a powerful predictor of developing hypertension. Age and obesity are also associated with increased risk of hypertension. Lifestyle modification might thus be necessary, particularly in subjects with proteinuria.