Ovarian dysgerminoma is usually hormonally inert, but when it contains syncytiotrophoblastic giant cells or undergoes malignant transformation, the level of estradiol might be elevated. A 6-year-old girl contracted ovarian dysgerminoma with precocious puberty, and her levels of beta-human chorionic gondaotropin, alpha-fetoprotein and estradiol were high. After resection of the tumor, levels of tumor markers became normal and precocious puberty disappeared. We report this unusual type of dysgerminoma with a brief review of the literature.