The purpose of this article was to describe the phenomenon of a new disorder called orthorexia nervosa. This paper proposes a theoretical framework for the definitions, prevalence, diagnostic criteria, method and treatment of orthorexia. This disturbing behaviour concerns the pathologic obsession for healthy nutrition. In contrast to eating disorders, people with orthorexia are obsessed with food quality rather than quantity and they do not care excessively for thin silhouette like in the case of patients with anorexia and bulimia nervosa. Individuals with orthorexia nervosa are obsessive about healthy food, leading to dietary restrictions and to a variety of negative psychological and social outcomes. The results of previous research show that on the one hand orthorexia is related to anorexia and bulimia nervosa, and on the other hand this syndrome is more closely allied with obsessive-compulsive disorders. In view of the studies presented here we could treat orthorexia as a disturbed eating habit which is connected with obsessive-compulsive symptoms.