Anorexia nervosa (AN) is a chronic psychiatric disorder with a high prevalence of 0.6% and the highest mortality rates among psychiatric diseases, around 10%, mostly due to undernutrition and suicide. AN is characterized by physiological features with a body mass index less than 17.5kg/m(2), low bone mineral density and amenorrhea, psychological symptoms with a distortion of image body, and behavioral abnormalities. Estrogen molecules and estrogen biological pathway are clearly involved in food intake and body weight in animals and humans. Further, hypoestrogenism has been demonstrated in AN patients and convergent evidence involves the estrogen pathway in the development of AN. AN presents a high heritability and polymorphisms in genes coding the estrogen receptors alpha and beta have been found significantly associated with the disorder. This chapter shows the implication of estrogens in AN and suggests investigation to develop future pharmacological treatments for anorexia.