Dyskinesias are hyperkinetic and involuntary movements that may result from any of a number of different genetic, infectious, and drug-induced causes. Some of the hereditary dyskinetic syndromes are characterized by paroxysmal onset of the abnormal movements. The classification of the familial paroxysmal dyskinesias (FPD) recognizes several distinct, although overlapping, phenotypes. Different forms of the disorder include attacks that are (1) induced by sudden movement (kinesiogenic);(2) spontaneous (non-kinesiogenic); and (3) induced by prolonged periods of exertion. Linkage analysis was pursued in a family segregating an autosomal dominant allele for non-kinesiogenic FPD. The disease allele was mapped to a locus on chromosome 2q31-36 (LOD score 4.64, theta= 0). Identification of distinct genetic loci for the paroxysmal dyskinesias will lead to a new genetic classification and to better understanding of these disorders.