Familial glucocorticoid deficiency (FGD) has long been recognised as a clinical entity, but molecular studies have so far been performed in only a few individuals. We describe a girl born to consanguineous Pakistani parents with clinical and biochemical features of FGD who is homozygous for the R146H mutation of the adrenocorticotropic hormone (ACTH) receptor gene. This mutation creates a new restriction enzyme site in the ACTH receptor gene, allowing accurate characterisation of the mutation without DNA sequencing. Our patient is the third child reported to be homozygous for the R146H mutation. Interestingly, she has a tall stature, a clinical finding reported in several children who have ACTH insufficiency and mutations of the ACTH receptor gene. We suggest that mutation analysis of the ACTH receptor gene be considered in children with clinical features of FGD and tall stature.