Both Anorexia Nervosa (AN) and Bulimia Nervosa (BN) are marked by a serious course and outcome in many of the afflicted individuals. In AN, there are an almost 18-fold increase in mortality including a high suicide rate, chronic courses in approximately 20 per cent of the cases, and more than half of the patients showing either a complete or a partial eating disorder in combination with another psychiatric disorder or another psychiatric disorder without an eating disorder. Mitigating factors of the outcome include onset of the disorder during adolescence and longer duration of follow-up. Vomiting, bulimia and purgative abuse, chronicity, and obsessive-compulsive features represent unfavourable prognostic factors in various studies. The longer-term outcome of BN is only slightly better result as compared to AN; however, the rate of mortality is low. Diagnostic crossover from bulimia nervosa to other eating disorders is a rather rare phenomenon, whereas the high rates of partial eating disorders may explain a large proportion of chronic courses. Social adjustment and the quality of personal relationship normalize in the majority of the affected patients. At present, the study of prognostic factors in bulimia nervosa does not allow any definite conclusions.