Many patients who are referred for physical therapy take medications that affect either their physiological responses to exercise or their ability to exercise. The purpose of this article is to discuss how medications potentially can affect cardiovascular responses to exercise. The effects of selected medications on heart rate, blood pressure, and electrocardiographic responses during exercise; on exercise performance; and on training adaptations are discussed. The types of medications included in this review are beta-adrenergic receptor antagonists, vasodilators, diuretics, digitalis, and antiarrhythmic agents. The mechanisms of action and the clinical indications are described for each category of drugs. Ways in which each of the categories of drugs interacts with exercise responses, exercise performance, and training adaptations are described. Knowledge of a person's medications can provide valuable information on current physical condition and medical history and can alert therapists as to how exercise responses may be altered. Potential complications that are likely to occur during exercise can be identified, facilitating the design of safe and effective treatment programs.