A large family with Pick's disease was re-examined after twenty years. Five new cases were found, one in the fourth and four in the fifth generation. This family now includes 25 patients with the clinical diagnosis Pick's disease, proven by autopsy in 14, and 7 patients in whom the same diagnosis was considered likely, over six generations. The additional information strongly supports the previously postulated dominant mode of inheritance in this family. In connection with the possible hereditary nature of Pick's disease in general, data on reported families in which the disease occurred in two or more generations and unpublished data on three other families are discussed. Since the diagnosis Pick's disease was certain in affected members of this family, the value of and computerized tomography could be assessed. Persons at risk but without clinical signs of the disease were investigated in the same way, and in 4 cases out of 12, distinct frontal atrophy was found. In one of these cases clinical signs of Pick's disease became manifest a year after the investigation.