Psychodynamic clinicians have long stressed the role of defense mechanisms in diagnosis and treatment of their patients. However, until recently the defense mechanisms were not the focus of extensive empirical research due to methodological limitations. The inclusion of defensive functioning scale (DFS) in DSM-IV has renewed the interest in psychodynamic approaches to clinical diagnosis, particularly the axis II syndromes in which the use of some defenses have long been considered important. Along with this, a number of prominent theorists like Millon, have linked each pathological character style to a particular defense mechanism. Despite the dearth of empirical research, the existing findings suggest that defenses have strong relationships with adult personality functioning and psychopathology, and DFS ratings have the potentials for adding clinically useful information to the diagnostic process.