Historical bases for the special role of the prefrontal cortex are outlined and the case of a 27-year-old woman with massive bilateral prefrontal damage of unknown etiology is then described. Frontal lobe degeneration was repeatedly examined with magnetic resonance imaging and fluoro-deoxy-D-glucose-positron emission tomography and was found to include both orbital and dorsolateral aspects of the frontal lobes. While the degeneration initially measured was limited to portions of the orbital, medial and dorsolateral parts of both frontal lobes, with right-sided predominance, a second brain scan 15 months later revealed massive shrinkage of both frontal lobes, together with additional involvement of the posterior association cortices. The patient had completed her high-school education and had superior verbal long-term memory, normal short-term memory, and normal priming, but manifested grossly deficient scores in various frontal lobe-sensitive tests. Though a number of neurological examinations were performed, no plausible cause for the damage was established.