Sexual assault as a major psychological trauma and a crime of violence evokes immediate symptoms of posttraumatic stress and, for many victims, long-term post-traumatic psychological sequelae. The victim, as the recipient of the rapist's anger and need to control, experiences terror, fear of death, and helplessness. This results in classic posttraumatic symptoms of haunting, intrusive recollections, numbing or constriction of feelings and focus, and increased arousal. When this psychological trauma is not integrated, anxiety, depression, phobias, impaired sexual and social adjustment, negative self-image, and diminished capacity to enjoy life follow. Concepts of posttraumatic stress are reviewed and a definition of sexual assault is offered. The posttraumatic stress response to sexual assault is considered under the phases of response and symptoms, followed by the psychodynamics of this particular psychic trauma. A brief overview of treatment is outlined.