The Honolulu Heart Study was a nested case-control study examining aCL as a risk factor for ischemic stroke and MI.819 The study used stored frozen sera obtained from subjects in the Honolulu Heart Program who were followed for up to 20 years. aCL ( 2 GPI] dependent) was tested in 259 men who developed ischemic stroke, 374 men who developed MI, and a control group of 1360 men who remained free of both conditions. aCL was significantly associated with both incident ischemic stroke and MI. Men with a positive aCL had higher risk of stroke relative to men with negative CI, 1.0 2.3] at 20 years). These data suggest that aCL is an important predictor of future stroke and MI in men. The Framingham Offspring Cohort Study, a longitudinal observational study, used an ELISA to measure aCL from stored frozen sera. This study found an association between aCL titers and ischemic stroke or TIA, but only in women.820 Overall, although elevated aCL titers may be commonly found in isch- emic stroke patients, the strength of the association between elevated aCL titers and stroke origin or risk is uncertain. The shortcoming of many studies evaluating aCL in stroke patients such as the Framingham Offspring Cohort study has been the use of the aCL ELISA, a test with low sensitivity. The assay for anti- 2 GPI antibodies, a cofactor for antiphospho- lipid binding, may be more specific for thrombosis, including stroke and MI.819,821 Only a few studies have investigated 2 GPI in the absence of SLE. 819,821,822 Because most studies involved patients with SLE, lupus anticoagulant, or aCL, it is difficult to establish the value of anti- 2 GPI as an independent risk factor. 