Puberty refers to a collection of somatic and psychic maturation phenomena, leading from juvenile to adult state. It is characterized by the development of secondary sex characteristics, growth spurt and changes in body composition and bone mineralization. It leads to the establishment of the reproductive function. The onset of puberty is influenced by environmental and neuroendocrine factors. A few diagnostic tests can prove useful to confirm the onset of puberty: bone age x-rays, pelvic echography in girls, estradiol assay in girls and testosterone assay in boys.