In 27 subjects, we compared rest and exercise blood pressure (BP) measurements determined directly by catheterization of the radial artery with simultaneous values obtained indirectly by auscultation of the brachial artery. As work increased, the systolic BP increased, whereas the diastolic BP did not change. Considering all comparisons, direct BP was greater than indirect BP by a mean of 29.0 mm Hg for systolic BP and 12.3 mm Hg for diastolic BP. As exercise level increased, the difference between direct and indirect systolic BP decreased whereas the difference between direct and indirect diastolic BP did not change. Both methods have advantages for assessment of BP response to exercise: normality of BP response is best assessed by auscultation, whereas beat-by-beat trends in BP are more accurately defined by the direct method.