This chapter discusses the endurance sports are defined as continuous activities of greater than 90 min duration that can potentially span into ultra-endurance events and multiday competitions. A common element to endurance sports is that fluid intake during an event is primarily achieved on the run-or while the athlete is actually exercising. The chapter also discusses the background to the debate over fluid needs for endurance events, covering the evolution of the guidelines and the points of differences in current views. In proposing recommendations to find some common and practical middle-ground, the literature on self-chosen fluid intakes of competitors in a variety of endurance sports will be presented. The updated American College of Sports Medicine guidelines published in 1996 increased the general scope of interest to fluid intake during exercise and recognized the benefits of including carbohydrate and electrolytes in beverages for endurance sports. The topic of recent debate has been the need for guidelines for fluid intake.