The antisocial personality disorder (ASPD) diagnosis has generated controversy because of its emphasis on antisocial behaviors and its limited attention to psychological traits of psychopathy, such as lack of loyalty, remorse, and anxiety. We examined the relationships between one psychological trait of psychopathy, lack of remorse, and phenomenology of ASPD, drug history, preadmission psychosocial functioning, and characteristics of index episode of treatment among 140 drug abusers with DSM-III-R ASPD enrolled in residential addictions treatment. Lack of remorse was associated with a more severe and more violent form of ASPD and increased comorbidity with mood and anxiety disorders. Implications for tailoring addictions treatment to antisocial clients who lack remorse include the need to identify and treat comorbid emotional disorders.