A 35-year-old woman with a 17-year history of anorexia nervosa (AN) sustained a pathologic fracture of the hip. Osteoporosis was confirmed by quantitative computed tomography of the lumbar spine and transiliac bone biopsy. Severe bone disease may exist in the anorexia nervosa syndrome and may to some extent be reversible on treatment of the underlying condition. AN could have profound effects on the peak bone mass achieved in the lifetime of the individual. Asymptomatic and symptomatic osteoporosis in young women may be based upon AN. Patients should be informed that osteoporosis can cause pathologic fractures as a sequela of self-imposed chronic malnutrition.