An overview of post-traumatic stress disorder, including a brief historical survey, & its epidemiology, nosology, etiology, clinical presentation, treatment, & prognosis, highlights the fact that this disorder prevails in times of war & peace. Early intervention is emphasized as the key to successful treatment. A short vignette is presented of a subway driver who experienced post-traumatic stress disorder, with suicidal ideation, after a subway incident in which a woman was killed. (82 refs.)