Background: The Japanese primary prevention of atherosclerosis with aspirin for diabetes (JPAD) trial was undertaken to examine the efficacy of aspirin therapy. Multicenter， prospective， randomized， openlabel， blinded， end-point trial conducted from 2002 through 2008 at 163 institutions throughout Japan， which enrolled 2539 patients and had a median follow-up of 4.37 years. A total of 154 atherosclerotic events occurred: 68 in the aspirin group and 86 in the nonaspirin group.
　　Methods: In the subgroup analysis of the JPAD study， we divided the patients into hypertension group or control group according to blood pressure when enrolled. We examined whether the incidence of cerebrovascular events or ischemic heart disease was influenced by hypertension， and also examined whether there were any differences in the influence of hypertension between the aspirin user and nonaspirin user.
　　Results: The stroke events occurred in 42 patients of the hypertension group (n=975) and 31 patients of the control group (n=1564) in the all JPAD patients. There was no significant difference in the incidence of the stroke events between the hypertension group (17 patients of 511) and the control group (16 patients of 751) in the aspirin user. On the other hand， there was a significant difference between the hypertension group (25 patients of 464) and the control group (15 patients of 813) in the nonaspirin user.
　　Conclusions: Subgroup analysis of the JPAD study indicates that blood pressure control is significantly associated with the incidence of stroke events. The aspirin therapy is important for primary prevention of stroke events especially in poorly blood pressure controlled patients with diabetes.