We evaluated the effect of endogenous estrogen levels on exercise-related changes in right ventricular systolic pressure (RVSP) of healthy, eumenorrheic, sedentary women. Volunteers were studied at two separates phases of the menstrual cycle (LO and HI estrogen phases), exercised on a semi-supine ergometer with escalating workload and monitored continuously by 12-lead ECG and automated blood pressure cuff. At each exercise stage, Doppler echocardiography measurements were obtained and analyzed to determine RVSP. Fourteen subjects (age 24 ± 5) were studied. Exercise duration was significantly higher on the HI estrogen day, but no significant differences in hemodynamic response to exercise were found between the two study days. There were also no significant differences with respect to heart rate (HR) acceleration during early exercise, as well as resting and peak RVSP, HR, blood pressure, and rate pressure product. Doppler-estimated RVSP demonstrated a linear relationship to HR at a ratio of 1 mm Hg (1 mm Hg = 133.3224 Pa) for every 5 bpm (beats per minute) increase in HR. There were no differences in the slope of this relationship between HI and LO estrogen phases of the menstrual cycle. Our findings did not demonstrate any effect of endogenous estrogen levels on the modulation of the pulmonary vascular response to exercise in healthy women.