As part of an ancillary study to the Systolic Hypertension in the Elderly Program, carotid and lower extremity arterial disease (LEAD) were evaluated in 369 subjects, 186 with a systolic blood pressure (SBP) > or = 160 mmHg, and 183 with SBP < 160 mmHg. Both groups had a diastolic blood pressure (DBP) < 90 mmHg. Internal carotid stenosis was identified by Doppler and LEAD was assessed using the ankle to arm systolic blood pressure ratio, commonly called the ankle/arm index (AAI). Lp(a) values were obtained from frozen sera and values > or = 20 mg/dl were considered elevated. Rates of carotid stenosis were 24% among those with an Lp(a) > or = 20 mg/dl and 14% among those with an Lp(a) level < 20 mg/dl (P = 0.020). The relationship between Lp(a) and LEAD was even stronger. Those with an Lp(a) > or = 20 mg/dl had a 36% prevalence of a low AAI vs 14% among those with a Lp(a) level < 20 mg/dl (P < 0.001). Lp(a) values were also associated with the severity of LEAD. Controlling for other risk factors did not reduce the association between either LEAD or carotid stenosis and an Lp(a) > or = 20 mg/dl. Thus, Lp(a) appears to be independently associated with peripheral atherosclerosis in older adults, both men and women. The relationship is particularly strong for atherosclerotic disease of the lower extremities.