This chapter focuses on the effects of acute doses of caffeine on the cardiovascular system, emphasizing the immediate impact on hemodynamics and heart function and implications of the short-term changes for potential long-term effects of the drug. The acute cardiovascular effects of caffeine are related to and, to some extent, stem from the arousal properties of the drug, which are well-demonstrated. Caffeine is known to increase arousal, so it is reasonable to ask whether or not it consistently increases heart rate and, if so, whether or not it may contribute to atherosclerosis. Despite the possible deleterious effect of caffeine in furthering arterial stiffness, some studies suggest that the drug may also, indirectly, improve heart function and potentially reduce morbidity and mortality. Results showed that caffeine maintained physical performance, even with sleep loss, and that time to exhaustion increased by 25% under influence of the drug.