Ultrasonography(US) is noninvasive, painless, and reliable study method in the evaluation of children and adolescents with precocious puberty. Breast US is useful to estimate breast development in prepubertal children with breast budding and distinguish pseudogynecomastia in obese boy. Morphologic characteristics of ovary and uterus is essential for diagnosis of prepubertal girls. So, the transabdominal pelvic sonography is effective tool. Increased measurements of ovary and uterus are helpful in diagnosis of precocious puberty. The purpose of this exhibit is to describe the breast and pelvic US findings in diagnosis and estimate of treatment of precocious puberty.