Anorexia nervosa in children and adolescents is still a serious cause of morbidity and mortality which may result in premature death or life-long medical and psychosocial morbidity. This condition can cause significant medical complications in every organ system of the growing and developing body. Although many of these medical complications improve with nutritional rehabilitation and recovery from the disorder some are potentially irreversible. This article summarizes the evidence based literature on medical complications that has been specially studied in child and adolescent population with anorexia nervosa over the past two decades. This review of the literature focuses on the acute symptoms of anorexia nervosa with special emphasis on the fluid and electrolyte levels and refeeding syndrome, and details the cardiovascular complications. Summarizes the special alterations in childhood and adolescent anorexia nervosa such as impaired bone mineral accretion and the possible therapeutic interventions of osteopenia and alterations in linear growth. The reviewed literature suggests that the medical complications in adolescents with anorexia nervosa are different from those reported in the adult population. The unique clinical presentation, the early onset and the unknown impact of these complications underline the need for early identification and early efficient treatment of anorexia nervosa in adolescents. There is an increasing number of evidence that highlight the importance of interdisciplinary teams of healthcare providers in the identification and in the therapy of adolescent anorexia nervosa as well.