Exercise Doppler echocardiography allows measure valvular gradient during exercise, that could be useful in the prescription of physical activity in patients with a prosthetic aortic valve.Exercise Doppler echocardiography was performed in 50 patients (mean age 53 +/- 12 years) with normally-functioning aortic prosthesis. Maximal exercise was performed by supine bicycle ergometry in 35 and modified Bruce protocol in 15. Continuous wave Doppler examinations were obtained at rest, during and at maximal exercise with a nonimaging transducer.The mean value of workload was 6.9 +/- 2 METS and there were no complications. Gradients at peak exercise were available in 43/50 patients. Exercise induced a statistic significant increase in the heart rate (76 +/- 14 to 136 +/- 26), systolic blood pressure (128 +/- 19 to 182 +/- 19 mmHg), peak gradient (29 +/- 9 to 61 +/- 17 mmHg) and mean gradient (16 +/- 5 to 32 +/- 9 mmHg). The gradient was greater than 59 mmHg in 18/43 patients, greater than 69 mmHg in 12/43 and greater than 79 mmHg in 5/43.Prescription of exercise in patients with aortic prosthesis requires perform an exercise Doppler echocardiography to measure the increase of valvular gradient with the exercise in each patient, since the stress testing could be normal, it can advise a rate of physical activity that determine very high prosthetic gradients.