OBJECTIVE: To study the causes and prognosis of peripheral precocious puberty. METHODS: The levels of follicle stimulating hormone (FSH), luteinizing hormone (LH) and estradiol (E2) were detected by a simplified gonadotrophin-releasing hormone (GnRH) stimulation test. The etiologies of 125 children with peripheral precocious puberty were explored by ultrasound scans and bone age assessment. A total of 102 cases were followed up for 3 months to 7.5 years. RESULTS: The etiological distribution of these children was as follows: exogenous hormones intake (n=80), ovarian cyst (n=11), McCune-Albright syndrome (n=11), congenital adrenal hyperplasia (CAH) (n=5), ovarian teratoma (n=1), masculine adrenal tumor (n=1), feminine adrenal tumor (n=1), and handle pituitary tumor (n=1). The causes in 14 cases were unknown. Follow-up showed that the sexual characteristics of 72 cases due to exogenous hormones intake subsided after 1-6 months. Of 11 cases with ovarian cysts, the sexual characteristics subsided spontaneously in 8 cases after 1 to 4 months, but one case was transformed to central precocious puberty after 2 years and three months. One child with ovarian cysts underwent an operation and than the sexual characteristics subsided. The sexual characteristics of the patient who had an ovarian teratoma subsided after operation. The clinical symptoms of children with McCune-Albright syndrome or CAH were alliaviated partly after treatment, and 7 cases were transformed to central precocious puberty. The clinical symptoms of 2 cases of adrenal tumors subsided after operation. One child with handle pituitary tumor died one year after operation. CONCLUSIONS: Varied causes may contribute to peripheral precocious puberty and therefore must be carefully identified through history taking, physical examination, and auxiliary examinations. The prognosis may differ for patients with different etiologies of peripheral precocious puberty.