To elucidate the clinical significance of lipoprotein(a) [Lp(a)] in the elderly, 48 patients with Lp(a) of 35 mg/dl or more [the high Lp(a) group] and 97 patients with Lp(a) less than 20 mg/dl [the low Lp(a) group] were enrolled to investigate their outcome for five years. At registration, they were all examined by brain computerized tomography (CT) for cerebrovascular diseases, B-mode ultrasonography (US) for carotid lesions, ECG for myocardial ischemia, and Doppler arteriography for the ankle pressure index (API). They were followed up completely to study survival rates, cause of death, and morbidity rates of vascular events, including occurrence of stroke, myocardial infarction, and aortic aneurysm as well as progression of the stage in arteriosclerosis obliterans. The mean age of the high Lp(a) group was 78.1, whereas that of the low Lp(a) group was 76.8. Baseline clinical findings revealed no difference in age or gender between the two groups, although a previous history of stroke, abnormal CT and US findings, and low API were more frequent in the high Lp(a) group than in the low Lp(a) group. In the high Lp(a) group [vs. the low Lp(a) group], 18 patients (vs. 21 patients) died within five years, which resulted in a cumulative mortality rate of 37.5% (vs. 21.6%) and an annual mortality rate of 9.4% (vs. 4.8%). Based on log-rank analysis, the survival rate of the high Lp(a) group was significantly lower than that of the low Lp(a) group. The most common causes of death were vascular events and pneumonia, more than half of them were aspiration pneumonia complicated with stroke. Ten patients in the high Lp(a) group had vascular events (vs. 8 patients). The morbidity rate of vascular events, most of which were cerebral infarction, was higher in the high Lp(a) group (annual morbidity rate 5.5%) than in the low Lp(a) group (1.8%). These findings suggested that serum Lp(a) concentration, genetically determined and remaining consistent throughout life, had influenced vascular wall damage over a long time with age, therefore, a high Lp(a) level might promote atherothrombosis. In the elderly, therefore, high Lp(a) level, resulting in symptomatic vascular lesions with organ dysfunction, is a distinct and independent poor prognostic risk factor.