Psychiatric nosology has characteristically been vague, imprecise, impressionistic and arbitrary. 1'2 Recently, however, there has been a revitalized interest in developing stricter diagnostic criteria and legitimizing diagnostic categories by specific inclusion criteria, family history studies and outcome studies. 3 This paper, discussing one of the least sharply defined, yet most commonly used diagnostic entities--the hysterical personality--focuses on what has been called the sick (oral, primitive, hysteroid, infantile) hysteric. Although many patients in this group may indeed be sick and do manifest prominent hysterical mechanisms, their sickness lies in something other than hysteria. The hysterical mechanisms often serve to mask and distort morebasic underlying pathology, subsequently leading to misdiagnosis and inappropriate treatment. We will discuss three of the diagnostic groups often misdiagnosed as (sick) hysteric because of the facade of hysterical mechanisms or features: borderline personalities, Briquet's syndrome, and hysteroid dysphoria (depression). Proper diagnosis in these instances offers significant prognostic and treatment implication.