A linkage analysis between the Hunter syndrome locus (IDS) and four polymorphic loci of the Xq27-Xq28 region, DXS105, DXS98, DXS304, and DXS52, was performed in large families. A significant lod score was obtained between DXS304 and the Hunter gene (Zmax = 6.57 at theta max = 0.0). The Hunter gene can be localized within 7 cM of this marker. In addition, the translocation breakpoint of the Hunter female case described by J. Mossman et al. (1986, Arch. Dis. Child. 58: 911-915) was localized between DXS98 and DXS304 using somatic cell hybrids. These two results are in agreement and give the following order: DXS105-DXS98-IDS-DXS304-DXS52. Probes for these marker loci can thus be used for carrier detection.