Endurance sports encompass a broad range of events from marathons and triathlons to ultramarathons, long-distance cycling, skiing, and swimming. As these events have experienced a surge in popularity, we have a greater need to understand the associated medical risks. This article reviews the history of endurance races, reviews the most critical and common causes of cardiovascular, heat, electrolyte, and musculoskeletal injuries/illnesses, and discusses considerations for medical directors/personnel associated with such events.