OBJECTIVES: The purpose of this study was to determine the cross-sectional relation between myocardial perfusion and coronary heart disease (CHD) risk factors among adults with no clinical CHD. BACKGROUND: Clinical studies suggest that myocardial perfusion is often abnormal in individuals without CHD but with risk factors. Epidemiologic study in asymptomatic populations is lacking. METHODS: Two hundred twenty-two men and women, ages 45 to 84 years and free of a CHD diagnosis, in the University of Minnesota field center of the Multi-Ethnic Study of Atherosclerosis (MESA) had myocardial blood flow (MBF) determined using cardiac magnetic resonance imaging at rest and during adenosine-induced hyperemia. Perfusion reserve (PR) was calculated as the ratio of hyperemic to rest MBF. RESULTS: Both resting and hyperemic MBF were lower in men than in women, even after considering age and menopause. Hyperemic MBF was also significantly lower in subjects who were older, and in those with higher blood pressure, higher fasting glucose, and lower low-density lipoprotein cholesterol. After adjusting for age, gender, and race, reduced PR was independently associated with hypertension, higher diastolic blood pressure, and higher total and low-density lipoprotein cholesterol, but was not associated with cigarette smoking, obesity, physical activity, or diabetes. Moreover, hyperemic MBF and PR were correlated strongly and inversely with estimated 10-year CHD risk based on Framingham equations (p for trends: <0.0001). CONCLUSIONS: Coronary vasoreactivity is reduced in asymptomatic individuals with a greater coronary risk factor burden. Our study results imply that changes in coronary vascular reactivity, in response to risk factors, may be detected in adults without symptomatic CHD.