Ectodermal dysplasia (ED) represents a heterogeneous group of genetic disorders characterized by the absence or deformity in two or more of the ectodermal appendages. We have studied an autosomal recessive form of ED in 13 individuals over six generations from an inbred Pakistani family. The clinical features of the affected individuals include highly dystrophic nails and thin hair on scalp, fine eyebrows and eyelashes, and thin body hair. Genome-wide linkage analysis of 390 microsatellite markers mapped the ED gene to the 3.92 cM interval flanked by markers D10S1710 and D10S1741 on chromosome 10q24.32-q25.1. Multipoint linkage analysis generated a maximum logarithm of odds ratio score of 4.79 in the interval D10S1239-D10S1264, which corresponds to 6.35 Mb.