The primary immunodeficiency with natural-killer cell deficiency and adrenal insufficiency is characterized by a specific natural-killer (NK) cell deficiency and susceptibility to viral diseases. It has been described in four children from a large inbred kindred. Three out of the four children reported developed a viral illness. The mode of transmission is most likely autosomal recessive. The causative gene has been localized to within a 12-Mb region on chromosome 8p11.23-q11.21.