Anemia is a common disorder among adolescents regardless of level of physical activity. The major cause of anemia in adolescents is nutritional iron deficiency. Iron metabolism may be altered in some athletes training and competing in endurance sports. The dilutional "sports anemia" that can occur in the more elite adolescent athlete may be an adaptation to aerobic conditioning. Screening for anemia in adolescent athletes is warranted because anemia may contribute to morbidity and diminished exercise performance. Current concepts and controversies regarding anemia in adolescent athletes are addressed, and application of this information to preparticipation physical examinations is examined.