Much of the evidence for recommendations regarding electrocardiogram (ECG) treadmill stress testing has come from studies involving middle-aged men. Special consideration must be given when deciding who, when and how to screen for cardiovascular disease in patients who fall outside of this category. There is less data on noninvasive testing in women, older adults and people with diabetes, although this issue is being recognized and addressed through recent studies and literature. The previous conception that coronary artery disease is only a disease found in men is quickly being replaced. Clinicians are recognizing that different standards must be used for identification of patients at risk, testing protocols and test interpretation. This chapter addresses the use of ECG treadmill stress testing in women, the elderly and persons with diabetes.