A modified Doppler ultrasound system has been developed which enables blood pressure measurements to be made noninvasively while a patient is undergoing a treadmill stress test. This system amplifies the Korotkoff sounds to an audible level while minimizing noise artifact, which was a problem in previous blood pressure monitoring systems. An investigation was also initiated to test the significance of using blood pressure measurements and the associated heart rate during the stress test as an additional diagnostic aid in the detection of coronary heart disease. The result of multivariate-discriminant analysis indicates that a possible difference exists in the relationship between systolic blood pressure and heart rate at increased levels of stress for normal patients, compared to those with coronary heart disease. Comparison with arteriography indicates that the stressed blood-pressure versus heart-rate relationship is a good indicator of coronary heart disease.