McCune-Albright syndrome is one of the causes of isosexual precocity in girls. Recurrent ovarian cysts are not uncommon in McCune-Albright syndrome; however, treatment for these cysts is still controversial. We report on a six-year-old girl with sexual precocity due to recurrent ovarian cysts. Initially, she received a left salpingo-ophorectomy for an ovarian cyst at the age of two years and one month; the postoperative course was uneventful. Unfortunately, sexual precocity and a cyst on the remaining ovary were noted four years later. A series of studies revealed a hyperpigmented area with an irregular margin on the back and probable fibrous dysplasia of the orbital bone. A luteinizing hormone-releasing hormone test showed a prepubertal response. Cyproterone acetate was tried under the diagnosis of McCune-Albright syndrome, and her secondary sexual characteristics disappeared after treatment.