Kallmann syndrome is defined by the association of hypogonadotropic hypogonadism and anosmia. A previously unreported association of Kallmann syndrome and choanal atresia in a family is reported. The mechanism of the embryopathic association of hypogonadotropic hypogonadism, anosmia, and choanal atresia is though to be due to a single developmental field defect in the region of the median forebrain and associated structures. An irregular autosomal dominant mode of inheritance is suspected.