X‐linked adrenal hypoplasia congenita (AHC) is caused by mutations in the NR0B1 gene. This gene encodes an orphan member of the nuclear receptor superfamily, DAX1. Ongoing efforts in our laboratory have identified nine novel NR0B1 mutations in X‐linked AHC patients (Y81X, 343delG, 457delT, 629delG, L295P, 926‐927delTG, 1130delA, 1141‐1155del15, and E428X). Two additional families segregate previously identified NR0B1 mutations (501delA and R425T). Sequence analysis of the mitochondrial D‐loop indicates that the 501delA family is unrelated through matrilineal descent to our previously analyzed 501delA family.