A form of autosomal dominant retinitis pigmentosa (ADRP) mapping to chromosome 17p has been reported in a single large South African family. We now report a new family with severe early onset ADRP which maps to 17p. Linkage and haplotype analysis in this family places the ADRP locus in the 5 cM interval between markers AFMc024za5 and D17S1845, confirming the data obtained in the South African family. The discovery of a second 17p linked family may imply that this is one of the more common loci for dominant RP. In addition, the confirmation of an RP diagnosis at this locus is of interest since loci for a dominant cone dystrophy and Leber's congenital amaurosis (LCA1) have recently been linked to the same markers. While the cone dystrophy locus may be allelic with RP, our data and that of Goliath et al show that distinct genes are responsible for dominant RP and Leber's congenital amaurosis on chromosome 17p.