Hereditary spastic paraplegias are neurological hereditary conditions of unknown aetiology. In pure spastic paraplegia, most of the pedigrees display an autosomal dominant mode of inheritance. A gene for pure autosomal dominant spastic paraplegia (ADSP), termed FSP1, was mapped to chromosome 14q in a large pedigree with early-onset disease. This locus was tested by linkage analysis in six large French kindreds of ADSP with late-onset disease, using four microsatellites spanning a 9 cM interval including FSP1. FSP1 could be excluded in five of the six families, while no evidence for linkage was found in the remaining family. These results suggest that FSP1 is not involved in late onset ADSP, at least in the six families studied.