Cardiovascular reactivity to stress has been proposed as a mechanism partially responsible for the increased prevalence of essential hypertension in African-Americans compared with whites. However, few studies have examined ethnic differences in cardiovascular reactivity among women. The present study evaluated potential ethnic differences in the cardiovascular reactivity to three laboratory stressors (postural change, video game challenge, forehead cold stimulation). The sample consisted of 171 normotensive girls (74 whites, 97 African-Americans) with a mean age of 11.1 +/- 2.7 years, all with positive family histories of essential hypertension. African-American girls showed higher resting diastolic blood pressures and higher resting total peripheral resistance compared with white girls. African-American girls also exhibited higher peak responses in systolic and diastolic blood pressure and total peripheral resistance and lower cardiac index responses during video game challenge and forehead cold stressor. The findings extend previous observations of ethnic differences in blood pressure reactivity to stress and indicate that concomitant increases in total peripheral resistance appear to account for the greater blood pressure reactivity in African-American girls.