Gonadal and olfactory features of Kallmann's syndrome, usually considered to be inherited as an X-linked recessive trait, were found in a father and son who both had cryptorchidism, hypogonadism, and hyposmia. The father's fertility had been induced with chorionic gonadotropin, leading to the birth of three children. Olfactory and gonadal functions were normal in the mother and two siblings. The father had low basal plasma testosterone and subnormal follicle stimulating hormone (FSH) response to luteinizing hormone-releasing hormone (LH-RH). The affected son and his healthy brother were prepubertal. Their basal plasma total and free testosterone, serum FSH and luteinizing hormone (LH), and response to LH-RH were similar. The clinical presentation and formal olfactory function studies were considered most helpful for the suggestive diagnosis of Kallmann's syndrome in children. The occurrence of this syndrome in this family is consistent with autosomal dominant inheritance.