The clinical features of four families with autosomal dominant spastic paraparesis (FSP) are described, along with the results of linkage analysis to markers from the regions of chromosomes 2, 14, and 15 which are known to contain spastic paraplegia genes. All families had 'pure' spastic paraparesis (FSP), but the severity of symptoms varied widely among families, and other mild neurologic signs were observed in some subjects. Although no family individually yielded a lod score >3.0, all families yielded positive lod scores with chromosome 2 markers, and a maximal lod score of 5.7 was obtained for the families combined using marker D2S352. There was no evidence of linkage to chromosome 14 or 15 in any of the families.