The authors performed psychodiagnostic, psychometric, and psychophysiologic evaluations on 37 patients referred by local surgeons approximately 2 years after tissue diagnosis of Stage I to III breast cancer. The Clinician-Administered Posttraumatic Stress Disorder (PTSD) Scale (CAPS) was used to classify patients into the following groups: "Current PTSD" (n = 5) "Past PTSD" (n = 7), and "Never had PTSD" (n = 25). Individualized "scripts" portraying personal life events were tape recorded and played back to the patients in the laboratory. Current PTSD patients showed significantly higher heart rate, skin conductance, and corrugator electromyogram responses during imagery of their personal breast cancer experiences than Past and Never patients. Physiologic responses were significantly and positively correlated with CAPS scores. These results provide psychophysiologic support for the proposition that a diagnosis of with a life-threatening illness can cause PTSD.