Objective: To evaluate ovarian function, especially ovulation rate, in adolescents with McCune-Albright syndrome (MAS) and a history of peripheral precocious puberty. Design: Prospective cross-sectional study. Setting: Academic center. Patient(s): A total of eight adolescents with MAS were compared with 15 healthy adolescents matched by age, Tanner stage and body mass index. Intervention(s): We determined basal gonadotropins, sex steroids, sex hormone binding globulin, anti-Mullerian hormone, glucose and insulin. A leuprolide acetate test was performed to measure luteinizing hormone (LH) and follicle stimulating hormone (FSH) (at 0 and 3 h), and 17B-estradiol, testosterone and 17-OH-progesterone (at 0 and 24 h). Salivary progesterone levels were used to assess ovulation during the 13th, 18th, 23rd and 28th days of each menstrual cycle for three to five consecutive cycles, and one pelvic ultrasound was performed during the follicular phase. Main outcome measure(s): Ovulation rate in adolescents with MAS. Result(s): The proportion of ovulatory cycles was 52.6% in controls compared with 35.7% in patients with MAS. Conclusion(s): The adolescent girls with MAS appear to have a lower ovulatory rate compared with controls.