Posttraumatic stress disorder (PTSD) is a disabling and prevalent psychiatric disorder. Researchers and scientists have developed a neurobiological basis, which provides a framework for understanding the complexities of PTSD, for many symtoms of the disorder. The estimated lifetime prevalence of PTSD among adult Americans is 7.8%, with women twice as likely as men to have PTSD. Onset of symptoms can occur years after exposure to trauma, and the duration of the illness can last a lifetime. Patients with PTSD often encounter multiple psychosocial problems that result from the symptoms they experience, and their distorted perceptions can affect relationships within the family and the workplace. Nurses in various roles (e.g., educator, therapist, prescriber, case manager, staff nurse) may encounter individuals with PTSD. The nursing profession has traditionally sought to explain sophisticated language to patients in understandable terms, and nurses serve in encouraging, supporting, and evaluating roles, all of which will be increasingly important as science and technology discover more information about the neurobiological basis for mental illnesses.