Hereditary dentatorubropallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disorder. Clinical and genetic findings in hereditary DRPLA are very similar to those of Huntington's disease (HD). However, it can be differentiated from HD by the pathological findings of dentatorubral and pallidoluysian atrophies and by a lack of prominent atrophy of the striatum at necropsy. The hereditary DRPLA gene has not been localised and the possibility that the two disease loci are allelic has been suggested. We have searched for linkage between the locus for hereditary DRPLA and D4S10 using the G8 probe, which is a genetic marker linked to HD. In four families, there were negative scores at all recombination fractions and the lod score was -2.215 at recombination fraction theta = 0.15. These data indicate that the locus for hereditary DRPLA is not closely linked to D4S10 and that hereditary DRPLA is a distinct disease from HD.