Congenital adrenal hyperplasia(CAH) is a recognized cause of precocious pseudopuberty. Some children with CAH also develop true precocious puberty with early maturation of the hypothalamic-pituitary-gonadal axis. We review a case of CAH who eventually developed central precocious puberty nine months after initial treatment with corticosteroid. A 3-year-old boy visited complaining of rapid growth, a large penis and frequent penile erections. This patient was diagnosed with CAH with elevated 17-OH progesterone and cortical hypertrophy of adrenal gland on CT scan. His gonadotropin levels were within the normal prepubertal range. Even on treatment with corticosteroid he grew rapidly and had testicular enlargement, pubic hair development and rapid bone maturation. At second admission, his gonadotropin levels were elevated both basally and in response to LHRH stimulation, suggesting that the CAH led to early activation of pubertal gonadotropin secretion(true precocious puberty). He was treated with monthly depot injections of a LHRH analog in addition to the hydrocortisone. His second sexual characteristics regressed gradually and rate of linear growth and bone maturation decreased.