Two cohorts of anorexia nervosa patients were followed up for a mean of 20 years. All except 4% of each cohort was traced. The crude mortalities were: St George's, 4%; Aberdeen, 13%. The SMRs were: St George's, 136; Aberdeen, 471. If the untraced were assumed to be dead, crude mortalities were 7.6% and 15.9% respectively, and SMRs were 276 and 592 respectively. Causes of death were complications of the illness and suicide. Medical treatment may reduce early mortality, while comprehensive medical and psychotherapeutic treatment may reduce late mortality.