Huntingtons disease (HD) is a hereditary disorder involving the central nervous system. Its effects are devastating, to the affected person as well as his family. The Department of Medical and Molecular Genetics at Indiana University (IU) plays an integral part in Huntingtons research by providing computerized repositories of HD family information for researchers and families. The National Huntingtons Disease Research Roster, founded in 1979 at IU, and the Huntingtons Disease in Venezuela Project database contain information that has proven to be invaluable in the worldwide field of HD research. This paper addresses the types of information stored in each database, the pedigree database program (MEGADATS) used to manage the data, and significant findings that have resulted from access to the data.