Norrie disease (ND) is an X-linked recessive disorder with congenital blindness (atrophia bulborum hereditaria, pseudoglioma). Six kindreds segregating for ND were studied for linkage with polymorphic markers of the human X chromosome. No recombination was observed between the ND-locus (NDP) and the DXS7 locus, the latter followed as a DNA-restriction fragment length polymorphism, detected by the recombinant DNA probe L1.28, and assigned to the region Xp11.2-Xp11.3. The maximum lod scores are zeta = 3.81 at theta = 0.00. Linkage data between NDP and the other genetic markers used in the present study are in keeping with this assignment of the mutation to the proximal Xp.