A case report of a premenarcheal patient with an ovarian torsion and mlleria n agenesis is presented. An 11-year old prepubertal girl presented with severe left lower quadrant abdominal pain and mild rebound. A computed tomography showe d a normal appendix; an ultrasound showed a left ovary measuring 3 ×2 cm with m ultiple 0.5-mm simple cysts. A diagnostic laparoscopy showed the left ovary tub e to be twisted, but the uterus was absent, and the right ovary and tube were no t visualized in the appropriate location; instead, a right adnexal structure was buried in the right sidewall. The ovary was untwisted and fixed to the pelvic sidewall. Chromosomes were 46,XX, and her hormonal evaluation was norma l. Ovarian torsion and mllerian agenesis are rarely reported. An association b etween the lax attachment of the adnexa and torsion may be a contributing factor in this condition. A case report of a premenarcheal patient with an ovarian torsion and mlleria n agenesis is presented. An 11-year old prepubertal girl presented with severe left lower quadrant abdominal pain and mild rebound. A computed tomography showe da normal appendix; an ultrasound showed a left ovary measuring 3 × 2 cm with m ultiple 0.5-mm simple cysts. A diagnostic laparoscopy showed the left ovary tub e to be twisted, but the uterus was absent, and the right ovary and tube were no t visualized in the appropriate location ; instead, a right adnexal structure was buried in the right sidewall. The ovary was untwisted and fixed to the pelvic sidewall. Chromosomes were 46, XX, and her hormonal evaluation was norma l. Ovarian torsion and mllerian agenesis are rarely reported. An association b etween the lax attachment of the adnexa and torsion may be a contributing factor in this condition.