The olfactory and gonadal dysfunction in Kallmann syndrome share a common embryologic pathophysiology. To characterize further the linkage between the hypogonadotropic hypogonadism and anosmia, the authors performed a detailed evaluation of olfactory function in a patient with Kallman Syndrome having the rare variant of partial gonadotropin deficiency (fertile eunuch). The subject was seen initially at age 16 years because of delayed puberty. He received testosterone replacement therapy and subsequently completed pubertal development. As an adult, while untreated, he had subnormal levels of serum testosterone, low gonadotropins, and normal response to luteinizing hormone- releasing hormone. He also had impotence that was reversible with testosterone therapy, and a normal sperm count. Despite the mild degree of hypogonadism, olfactory function was completely absent, and the response to nasal trigeminal stimulants was markedly attenuated. Complete anosmia may therefore be associated with gonadotropin deficiency that is only partial; the presence of anosmia does not predict the need for gonadotropin therapy to attain fertility.