Objectives: The aim of this study was to investigate the effects of DASH diet and law salt diet health education program on the blood pressure and the diet habit in the prehypertension group in Korea. Methods: The participants in this study were 141 people with prehypertension who were seen at a public health center. Data collection was done from March 11 to November 11, 2005 using interview with questionnaires. The participants took part in the diet health education program for 8 weeks. In order to evaluate the effectiveness of health education program, the variables of the diet such as hypertension, law salt diet and DASH diet were measured before and after the health education. The blood pressure was measured three times during the education. The collected data were analyzed with paired t-test and repeated ANOVA using SPSS 12.0 for Windows. Results: The diet habit variables after the education showed that their diet habit tend to the low salt diet and the DASH diet. The participants improved in their knowledge of hypertension and law salt diet, and they improved in the behavioral level of law salt diet and DASH diet after the health education for 8 weeks. Systolic and diastolic pressure were significantly decreased in prehypertension group after 8 weeks [10mmHg/6mmHg(p<0.001)]. Conclusion: These result suggest that the improvement in the level of behavior might be related with the change in blood pressure among the people having prehypertension in Korea.