Background-Factors leading differentially to the development of isolated diastolic(IDH), systolic-diastolic(SDH), and isolated systolic(ISH) hypertension are poorly understood. We examined the relations of blood pressure(BP) and clinical risk factors to the new onset of the 3 forms of hypertension. Methods and Results-Participants in the Framingham Heart Study were included if they had undergone 2 biennial examinations between 1953 and 1957 and were free of antihypertensive therapy and cardiovascular disease. Compared with optimal BP(SBP< 120 and DBP< 80 mm Hg), the adjusted hazard ratios(HRs) for developing new-onset IDH over the ensuing 10 years were 2.75 for normal BP, 3.29 for high-normal BP(both P< 0.0001), 1.31(P=0.40) for SDH, and 0.61(P=0.36) for ISH. The HRs of developing new-onset SDH were 3.32, 7.96, 7.10, and 23.12 for the normal BP, high-normal BP, ISH, and IDH groups, respectively(all P< 0.0001). The HRs of developing ISH were 3.26 for normal and 4.82 for high-normal BP(both P< 0.0001), 1.39(P=0.24) for IDH, and 1.69(P< 0.01) for SDH. Increased body mass index(BMI) during follow-up predicted new-onset IDH and SDH. Other predictors of IDH were younger age,male sex, and BMI at baseline. Predictors of ISH included older age, female sex, and increased BMI during follow-up. Conclusion-Given the propensity for increased baseline BMI and weight gain to predict new-onset IDH and the high probability of IDH to transition to SDH, it is likely that IDH is not a benign condition. ISH arises more commonly from normal and high-normal BP than from “burned-out”diastolic hypertension. Background-Factors leading differentially to the development of isolated diastolic (IDH), systolic-diastolic (SDH), and isolated systolic (ISH) hypertension are poorly understood. We examined the relations of blood pressure (BP) and clinical risk factors to the new onset of the 3 forms of hypertension. Methods and Results-Participants in the Framingham Heart Study were included if they had undergone 2 biennial examinations between 1953 and 1957 and were free of antihypertensive therapy and cardiovascular disease. Compared with optimal BP (SBP <120 and DBP <80 mm Hg), the adjusted hazard ratios (HRs) for developing new-onset IDH over the ensuing 10 years were 2.75 for normal BP, 3.29 for high-normal BP (both P <0.0001), 1.31 (P = for HRH, and 0.61 (P = 0.36) for ISH. The HRs of developing new-onset SDH were 3.32, 7.96, 7.10, and 23.12 for the normal BP, high-normal BP, ISH, and IDH groups, respectively <0.0001). The HRs of developing ISH were 3.26 for normal and 4.82 for high-normal BP (b Increased body mass index (BMI) during follow-up predicted new-onset IDH and SDH. Other predictors of IDH were younger (P = 0.24) for IDH, and 1.69 age, male sex, and BMI at baseline. Predictors of ISH included older age, female sex, and increased BMI during follow-up. Conclusion-Given the propensity for increased baseline BMI and weight gain to predict new-onset IDH and the high probability of IDH to transition to SDH, it is likely that IDH is not a benign condition. ISH arises more commonly from normal and high-normal BP than from “burned-out” diastolic hypertension.