The objective was to determine the effect of lifestyle modification on cardiovascular risk in individuals with prehypertension, which is defined as a systolic blood pressure between 120 mmHg and 139 mmHg and a diastolic pressure between 80 mmHg and 89 mmHg. A randomized clinical trial was carried out in prehypertensives to compare those who took part in a program involving dietary modification, physical activity and educational sessions with those who followed normal recommendations. Cardiovascular risk was evaluated using the Framingham risk score and the chi-squared test, the Mann-Whitney U-test and the Friedman test. The mean Framingham score in the intervention group decreased from 5 (rank, -10 to 12) to 3.5 (rank, -11 to 10; P< .05) and the probability of a cardiovascular event at 10 years decreased from 5.29+/-3.88 to 4.24+/-2.86 (P< .05). This improvement was associated with a relative risk of 0.30 (95% confidence interval, 0.11 to 0.83) and a relative risk reduction of -69.8% (95% confidence interval -89% to -16.9%). There was no change in control subjects. Lifestyle modification decreased cardiovascular risk in individuals with prehypertension.