• Studies have observed that black children exhibit greater blood pressure increases in response to dynamic exercise than white children. Seventy-five (51 white, 24 black) children aged 4 to 6 years old had their blood pressure and heart rate measured before, during, and 5 minutes after dynamic upright exercise on the treadmill. Girls had higher preexercise heart rate values than the boys, and showed a marginally slower recovery of diastolic blood pressure values. Black children had significantly lower preexercise and peak exercise heart rate values, higher systolic blood pressure values at peak exercise, and greater systolic blood pressure increases in response to exercise than did white children. These differences are discussed in terms of mechanisms that may be responsible for racial differences in essential hypertension.