Introduction: Estrogen deprivation has been related to arterial stiffness in women, and physical exercise is indicated for treatment of cardiovascular disorders and central arterial stiffness after menopause. This morpho-quantitative study evaluated the extracellular matrix of ascending aorta tunica media in ovariectomized female Wistar rats submitted to aerobic physical exercise, compared to intact and sedentary controls. Material and methods: Female Wistar rats were studied from six to nine months of age. They were divided into four groups: sedentary intact, sedentary ovariectomized, exercised intact and exercised ovariectomized. Exercised rats were subjected to a motorized treadmill at 60% of their maximum ability for one hour/day, five days/week for 12 weeks. Histological sections of aorta were stained to detect elastic lamellae, elauninic and oxytalan fibers, and collagen fibers by stereological methods. Results: In intact rats, exercise was associated with significantly greater volume density of elastic lamellae, oxytalan fibers, and collagen fibers, relative to being sedentary. In contrast, in ovariectomized rats, exercise was associated with decreased collagen fibers, relative to being sedentary. Conclusion: Aerobic physical exercise can decrease ascending aorta stiffness in female Wistar rats with low estrogen levels.