We report positron emission tomographic measurements of regional cerebral blood flow (rCBF) in a male patient with war and torture related post-traumatic stress disorder (PTSD) during symptom provocation. The subject was exposed to war related sounds before and after treatment with a selective serotonin reuptake inhibitor (SSRI; Fluoxetine; Fontex((R))). Therapy reduced PTSD symptoms, provoked anxiety and heart rate. Before treatment trauma reminders resulted in decreased rCBF in the insula, prefrontal, and inferior frontal cortices. Increased activity was evident in the cerebellum, precuneus and supplementary motor cortex. This was normalized after SSRI administration. Prefrontal and cingulate rCBF correlated with heart rate. Hence, the anxiolytic effect of SSRI for PTSD could be mediated by prefrontal and paralimbic cortices. Data suggest that SSRI treatment normalize provocation induced rCBF alterations in areas involved in memory, emotion, attention and motor-control.