The origins of dystonia musculorum deformans are now considered to be organic. However, misdiagnosis of dystonia as a functional psychiatric disorder—usually conversion reaction—has persisted. The present study describes personality traits as measured by the Minnesota Multiphasic Personality Inventory in 30 persons with dystonia and in a control group of 37 persons with cerebral palsy. The data, examined by diagnosis, level of disability, and sex, showed no differences for diagnostic groups or levels of disability. Males scored in the direction of greater psychopathology than did females. The male dystonics showed the highest elevations of MMPI scales of all the groups. Although only one person with dystonia musculorum deformans and none with cerebral palsy produced the profile usually associated with conversion reaction, 36% of all profiles showed two scales above a T score of 70. This finding suggested that young adults with a physically disabling disease may be at higher risk for developing maladaptive personality traits.