Hemodynamic responses to systematic variations in occupational stress were examined using ambulatory blood pressure monitors (ABPMs). The goals of this study were (a) to illustrate the effectiveness of employing naturally occurring, controlled variations in psychological stress levels in studies incorporating ABPMs and (b) to document the patterns of cardiovascular responses to acute examination stress in medical students. Heart rate, systolic blood pressure, diastolic blood pressure, rate-pressure product, and mood states were measured before, during, and after low-stress (lecture) and high-stress (examination) work in 44 healthy male medical students. The lecture day was characterized by stable patterns of cardiovascular activity across all three periods. Hemodynamic activity and reports of activation and distress were greater on the examination day than on the lecture day. Cardiovascular activity during the preexamination period was as high as that seem during the examination period itself, indicating an anticipatory stress effect. Pressor activity decreased after the examination, although some residual chronotropic activity was seen. Systematic changes in physiological responses to controlled variations in the level of this naturalistic stressor support the use of this paradigm for other ABPM studies. The elevations in preexamination responses seen here suggest the need to consider prestressor experiences in such studies.