Stepping as an exercise modality has gained increasing popularity. The step treadmill is an exercise machine which simulates actual stair-climbing. The purpose of this study was to determine the effectiveness of a 16-week supervised aerobic step treadmill exercise training protocol in reducing resting blood pressure in women with unmedicated mild hypertension. During the training protocol, subjects exercised during a self-selected appointment three times a week on the step treadmill, increasing from 20 minutes up to 60 minutes per session, at a target heart rate corresponding to 70-80% heart rate reserve for 16 weeks. Utilizing paired t-test analysis, mean resting systolic blood pressure decreased from 142.2 +/- 9.1 to 132.7 +/- 8.2 mm Hg (p < .01) and mean resting diastolic blood pressure decreased from 93 +/- 4.9 to 87.4 +/- 5.4 mm Hg (p < .01) during the 16-week protocol. Mean maximal oxygen uptake was significantly increased, whereas mean body weight did not change significantly over the 16-week period. Large scale trials are needed to further delineate the effectiveness of stepping as a health care intervention in adults with unmedicated mild hypertension, especially in women.