The familial nature of Tourette syndrome (TS) was first described by Georges Gilles de la Tourette in 1885. Formal investigations of TS since the 1970s have consistently demonstrated an increased risk for TS among relatives of patients with TS. Family studies, twin studies, and segregation analyses all indicate that TS has significant genetic determinants. The mode of transmission, while mildly controversial, is generally believed to be due to at least one major locus inherited either as an autosomal dominant trait with reduced penetrance, or as a trait with intermediate inheritance in which some heterozygotic persons manifest the disorder. There is evidence for a TS spectrum of symptoms that includes chronic tics and obsessive-compulsive disorder. Systematic genome linkage studies of TS are progressing. To date, however, no significant linkage findings exist, although the search has included many neurologically relevant candidate genes.