The absence of bearded axillary and pubic hair is seen in Klinefelter syndrome. It is also known as congenital testicular hypoplasia or Klinefelter’s syndrome. The typical karyotype is 47, XXY, and the phenotype is characterized by testicular hypoplasia. The body is elongated, due to an increase in the distance between the heel and the toe bones. In men, the mammary glands are developed, pubic hair is distributed in a feminine pattern, and the penis and testes are small. Severe cases are associated with mental retardation, cryptorchidism and hypospadias. Sometimes it can occur due to some organic diseases such as hypopituitarism, hypothyroidism, and testicular feminization syndrome. The following diseases are also causes of beardless axillary and pubic hair: 1. Male hypogonadism is a series of manifestations of testicular hypofunction due to various causes. The blood gonadotropin measurement can differentiate hypogonadism into two categories: primary or secondary, the former with elevated basal gonadotropin; the latter with reduced, LRH excitation test and chlorostigmine test can determine the reserve capacity of the pituitary gland, pituitary hypogonadism is a low response, hypothalamic sex is a low response or delayed response, primary hypogonadism is an active response, chorionic gonadotropin ( HCG excitation test, plasma testosterone is elevated at least 1-fold in normal males or children, plasma testosterone is also elevated after injection in cryptorchidism, but not in azoospermia, secondary sex characteristics development, testicular location, size, texture, and plasma testosterone levels, routine semen examination helps to establish the presence and extent of testicular insufficiency, karyotype analysis, and plasma dihydrotestosterone testing helps to further classification. 2. Erosive adenomatosis of the nipple is a type of adenoma of the papillary duct. This disease is rare, mainly in middle-aged women, but also in men. Idiopathic hypogonadotropic hypogonadism Hypogonadotropic hypogonadism (HH) includes a large group of disorders, including congenital GnRH neuron defects, pituitary gonadotropin deficiency or molecular structure abnormalities, chronic systemic diseases, mental stress, severe weight loss or prolonged strenuous exercise can cause gonadotropin deficiency. In addition, gonadotropin deficiency is a component of some congenital syndromes (e.g., Prader-Willi syndrome, Laurence-Moon-Biedl syndrome, etc.). The degree of gonadotropin deficiency is also heterogeneous, with complete absence of pubertal sexual maturation at one extreme and delayed puberty at the other, with varying degrees of excess types in between.