Hyperventilation has been reported to cause false-positive ischemic shifts in the ST-segment of the electrocardiogram during exercise. These responses have been observed to occur at a higher incidence in females than males. Therefore, the purpose of this study was to determine the effects of the performance of pretest hyperventilation on ECG components that are suggestive of myocardial ischemia in females. A standard 12-lead Mason-Likar recording set was used including leads I, II, II, aVR, aVL, aVF, V₂, and V₅. Fifteen females comprised the subject pool for this study, which was screened on the basis of J-point depression in a preliminary exercise procedure. The fifteen subjects each performed two exercise sessions, one with no hyperventilation and the other with a preliminary hyperventilation. Statistically significant differences were found between the baseline and post-hyperventilation ECG (P<.05). Analysis of the results revealed no significant differences in J-junction depression, ST slope, and the ST integral between the two testing conditions. Hyperventilation did affect the ST responses of the ECG in these young adult females at baseline and its continued use in conjunction with graded exercise testing may help uncover ST-segment changes associated with false-positive exercise responses. Hyperventilation may be performed in young adult females in conjunction with GXTs without the liklihood of augmenting ST-segment shifts during the exercise. / Master of Science