['The association between homocysteine and isolated systolic hypertension in older adults was evaluated using a case-control design, and the relationship between homocysteine and clinical or subclinical atherosclerosis was explored.', 'Cases were 179 adults > or = 60 years with a systolic blood pressure of > or = 160 mm Hg and diastolic blood pressure < 90 mm Hg. One hundred seventy-one control subjects had the same criteria except systolic blood pressures were < 160 mm Hg. All had normal creatinine levels. Homocysteine levels were performed on fasting blood samples that had been stored at -70 degrees C. Atherosclerosis was defined as either a history of clinical disease, an internal carotid stenosis of > or = 40% by duplex scan, or an ankle/arm pressure ratio of < 0.9. The median homocysteine value was 11.5 micromol/L for cases and 9.9 for control subjects (P<.001). After control for potential confounders, homocysteine remained significantly associated with systolic hypertension (P=.019). For the hypertensive group, there was no apparent association between level of homocysteine and prevalence of atherosclerosis. However, among the normotensive group, the prevalence of atherosclerosis went from 22% in the lowest quintile of homocysteine values to 53% in the fifth quintile, with an odds ratio of 4.1 (fifth quintile in comparison to the first, P<.05). After adjustment for age, sex, systolic blood pressure, cholesterol, and smoking, this odds ratio increased to 6.4 (P<.01).'] Are high homocysteine levels independently related to isolated systolic hypertension in older adults?