Eating disorders are prevalent in adolescents and are associated with significant medical and psychiatric morbidity. Amenorrhoea, one of the cardinal features of anorexia nervosa, is the most likely reason for consulting the gynaecologist. Amenorrhoea in a young woman should alert the gynaecologist to the possibility of an underlying eating disorder. Osteopenia is a potentially irreversible complication of prolonged amenorrhoea and a low oestrogen state. Eating disorders are best managed by a team approach, with the team comprising a physician, nutritionist and therapist. Oestrogen replacement therapy has not been shown to be an effective treatment for osteopenia in anorexia nervosa and the gynaecologist should avoid simply prescribing oestrogen replacement therapy without referring the patient for comprehensive treatment of the eating disorder. Nutritional rehabilitation, weight restoration and resumption of spontaneous menses are the mainstay of medical management. Calcium and vitamin D supplementation and moderate weight-bearing exercise should be prescribed where indicated. Newer therapeutic options for the treatment of osteopenia include DHEA, IGF-1 and alendronate.