A case of ovarian granulosa cell tumor as cause of female precocious puberty is reported with the brief review of literature. This case of 9 years old girl was admitted to our clinic because of irregular periodic genital bleeding, palpable mass and pain in lower abdomen, and premature appearance of secondary sex characters, such as hypertrophy of breasts, the appearance of axillary and pubic hair, puberal enlargement of the external genitalia, and also hypertrophy of uterus. The laparatomy and histopathologic studies revealed a child head sized, ovoid, hemorrhagic, necrotic, encapsulated, and firm right ovarian granulosa cell tumor weighing 610gm. After removal of tumor, signs of precocious puberty disappeared in about a month.