Exercise electrocardiogram forms the basis for diagnosis of ischemia in coronary heart disease. Blood pressure behavior, physical fitness, training heart rate and possible cardiac arrhythmias can additionally be assessed using bicycle ergometry or treadmill testing. When the indications for and contraindications to exercise testing (either bicycle ergometry or treadmill testing) are closely observed, serious complications are rare. However, it is important that the treating physician is aware of and able to recognize possible complications. The present article discusses possible cardiovascular complications and their incidence.