In the early 1970's, American researchers Sifneos and Nemiah, using the results of there own studies and those of Ruesch, McLean, Marty and others, proposed an original concept of psychosomatic disorders, called the concept of alexithymia. It has become very popular in many research centres in the USA, Germany and Italy. The concept has been based upon the role of the so called alexithymic personality traits, which were found more often in patients with psychosomatic disorders than in other patient populations. Alexithymia (lack of words for emotions) has been defined as a set of psychological dispositions due to specific deficits in emotional and cognitive areas. Persons with alexithymic features present difficulties in perception and verbalization of emotions, cannot distinguish between vegetative feelings and emotions, and possess externalistic, outwardly directed cognitive style. Initially, alexithymia was linked to the etiology of psychosomatic disorders. Later, it was found in other pathological conditions such as somatization disorder, post-traumatic stress disorder, alcohol and substance abuse, neuroses and also in normal population. The origin of alexithymic features is seen as the dysfunction of limbic system, abnormal cerebral lateralization as well as disturbances in early learning of verbal and emotional associations. Alexithymic traits are also regarded as a specific homeostatic mechanism allowing for nearly normal functioning at expense of somatization. Twenty years after, the concept of alexithymia is still a focus of interest in many scientific centres. The most active is a Canadian research group, the authors of Toronto Alexithymia Scale, which is now considered the best measuring tool for alexithymia. Alexithymia has now been regarded a permanent personality trait and alexithymia theory can make a new psychosomatic paradigm.