Two cases of Pick's disease are presented in which brain biopsy studies were made. The clinical, differential diagnostic, and neuropathological aspects of these cases are discussed.This long neglected and poorly understood clinical entity—the presenile psychosis —is now receiving the close attention and careful scrutiny of more progressive neuropathologists and biochemists. The emphasis is no longer on changes in morphology but rather on the alterations occurring in the metabolism of brain tissue. With newer methods and finer techniques we can look forward to a better understanding of previously obscure neuropsychiatric disorders.Abstract Teaser