The Sneddon syndrome was formerly thought to be a manifes- tation of aPL syndrome, but it may be present in patients with or without aPLs,817 and the risk of ischemic stroke is increased only in those patients with increased aPLs. Several prospective cohort studies have assessed the rela- tionship between aPL and ischemic stroke. Stored frozen plasma from the Physicians Health Study was used to deter- mine whether aCL was a risk factor for ischemic stroke and venous thrombosis in healthy adult men.818 This was a nested, case-control study in a prospective cohort with 60.2 months of follow-up. At entry into the study, 68% of 22071 partici- pants submitted plasma samples. A control was matched by age, smoking history, and length of follow-up to each of the 100 patients with ischemic stroke and the 90 patients with deep vein thrombosis or pulmonary embolus. The aCL titers were higher in cases with deep vein thrombosis or pulmonary embolus than in matched controls (P=0.01). People with aCL titers above the 95th percentile had an RR for developing deep vein thrombosis or pulmonary embolus of 5.3 (95% CI, 1.55 18.3; P=0.01). Although an aCL level above the 95th percen- tile was an important risk factor for deep vein thrombosis or pulmonary embolus, there was no effect on stroke (an RR of 2 for ischemic stroke could not, however, be excluded because of low power). 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. 