The objective of this study was to determine the factors that influence diastolic blood pressure (DBP) and the incidence of hypertension. In 1977, DBP and cardiovascular risk factors were measured in 7092 men and women. In 1995, 2335 subjects participated at a second screening. Those patients already under hypertension treatment in 1977 were excluded. The DBP tracking was studied in subjects not under hypertension treatment during the study. Hypertension was defined on two ways in the analysis: under current hypertension treatment or a DBP > 95 mmHg measured at rescreening in 1995. Forty-seven percent of the subjects with a DBP < 75 mmHg in 1977 remained in the same category of DBP in 1995, and 7% had become hypertensive. Of the 75-84 mmHg group in 1977, 40% stayed in the same category in 1995 and 15% became hypertensive. Of the 85-94 mmHg category, 30% stayed in the same category and 30% became hypertensive in 1995. Of the highest category in 1977 (> 95 mmHg), 64% were still in that category in 1995. Baseline DBP in 1977 had the highest predictive value for future DBP. Weight gain over the years increased the risk for future hypertension: in contrast, there was no risk at a low DBP without weight gain. There is no need for regular check-ups for those patients with a low DBP who experience no weight gain. Borderline DBP (85-95 mmHg), together with weight gain, increases the risk of development of hypertension. The risk was especially high for men in the lower socioeconomic class.