The authors report the case of a 20-year-old professional soccer player who underwent medical evaluation because of atypical chest discomfort and dizziness precipitated by strenuous effort. The ECG and echocardiogram findings were normal. The young athlete did a treadmill stress test which was negative for myocardial ischemia. His myocardial perfusion imaging and coronary angiography were also normal. Later during the investigation, he underwent treadmill stress echocardiography, during which he developed an intraventricular gradient of over 100 mmHg with end-systolic peak and systolic anterior movement (SAM) of the mitral valve. These echocardiographic findings were not present at rest and disappeared shortly after termination of exercise. The authors discuss the significance of these findings and their potential link to sudden death.