BACKGROUND: Acute ovarian torsion (OT) is an uncommon cause of abdominal pain in children and is frequently confused with other conditions. METHODS: We reviewed the records (1983 to 1999) of all children treated for acute OT at our children's hospital. RESULTS: Mean child age (n = 51) was 12.5 ± 0.3 years. Children presented with either right-sided (n = 29) or left-sided (n = 22) pain. Diagnosis of OT was confirmed preoperatively by ultrasound (73%) or computed tomography (CT) scan (10%) while nine children (17%) with right-sided pain underwent surgery for presumed appendicitis. Despite a relatively short time from diagnosis to surgery, all 51 children required salpingooophorectomy. Contralateral biopsy was performed in 29% and 57% had an appendectomy. Younger children more commonly had either a mature cystic teratoma or torsion with no underlying abnormality as an etiology compared with OT in older children that was more likely to result from either a follicular or corpus luteal cyst. Pathologic examination of the contralateral ovary and appendix was normal in all children who underwent biopsy and appendectomy. CONCLUSIONS: Ultrasonography with color doppler is helpful for differentiating acute OT from appendicitis. Although the twisted ovary can rarely be salvaged, the etiology is usually benign. Preoperative serum markers and contralateral ovary biopsy may be unnecessary.