Aspirin is now a useful therapy for both primary and secondary prevention for cardiovascular events especially in diabetic patients. Hypertension is also one of the major atherosclerotic risk factors. The authors studied the rate of aspirin use as primary prevention in hypertensive cases at Srinagarind Hospital, Khon Kaen University. There were 164 of 231 hypertensive patients who were aged over 50 years old and met the criteria for aspirin therapy with 2003 ESHs guideline. Only 18.9% (31 of 164 cases) were prescribed aspirin. The most common dose of aspirin was 60 mg/day which was lower than the suggested dose. Within one-year follow up, there was no serious side effects of the aspirin such as upper gastrointestinal bleeding.