DSM-IV: Dissociative Amnesia

Diagnostic criteria for 300.12 Dissociative Amnesia
(cautionary statement)  

A. The predominant disturbance is one or more episodes of inability to recall important personal information, usually of a traumatic or stressful nature, that is too extensive to be explained by ordinary forgetfulness. 

B. The disturbance does not occur exclusively during the course of Dissociative Identity Disorder, Dissociative Fugue, Posttraumatic Stress Disorder, Acute Stress Disorder, or Somatization Disorder and is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a neurological or other general medical condition (e.g., Amnestic Disorder Due to Head Trauma). 

C. The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.