This study examined the psychological impact of stalking upon female undergraduates, a population previously determined to experience a surprising stalking prevalence rate. Despite common understanding that stalking has deleterious effects, there have been no previous efforts to systematically assess them with standardized measures. Thirty-six female stalking victims were compared with 43 females who had been harassed and 48 controls. Psychological impact was assessed with the Posttraumatic Stress Disorder Scale, the Symptom Checklist-90-R, and the Self-Report Interpersonal Trust Scale. Stalked subjects endorsed significantly more PTSD symptoms and with greater severity than the harassed or control subjects. Stalked subjects also had significantly higher scores on several subscales of the SCL-90, and had significantly higher positive symptom totals and distress indices.