Ovarian steroid cell tumors are rarely encountered in prepubertal girls. The majority of these tumors produce hormones, testosterone being the leading one. These tumors may either coexist with or imitate congenital adrenal hyperplasia (CAH). We present a 13-year-old female patient who was diagnosed with non-classical CAH at six years of age while being investigated for premature pubarche. She was diagnosed with steroid cell ovarian tumor after a delay of six years. The diagnosis was based on radiologic imaging, which was performed to investigate causes of unsuccessful metabolic control while under high-dose steroid therapy. The right ovarian hypoechoic mass of 23x22 mm was excised laparoscopically, preserving the ovary. Immunohistochemical staining showed that tumor cells were strongly positive with inhibin and focally positive with vimentin. Based on these findings, the patient was diagnosed with ovarian steroid cell tumor not otherwise specified. In the postoperative second week, total testosterone level was <10 ng/ml, and 17 hydroxyprogesterone (17-OHP) level was 1.1 ng/ml. Peak 17-OHP level was 4.2 ng/ml on repeated ACTH stimulations, and the diagnosis of CAH was excluded. Steroid therapy was tapered down and then discontinued. It should be kept in mind that there may be a misdiagnosis in cases of CAH, which may present itself with unsuccessful metabolic control even while under the appropriate treatment dose. Early diagnosis and treatment would prevent the development of irreversible signs.