Background Torsion of the greater omentum is an uncommon cause of acute abdominal pain. Omental torsion can be divided into primary and secondary. Owing to its nonspecific abdominal pain, preoperative diagnosis is difficult. Ultrasound sonography and abdominal computed tomography scans do not have a major role in preoperative diagnosis. The definite diagnosis is usually made during operation. Case presentation A 7-year-old Persian boy was referred with right lower quadrant pain associated with nausea and vomiting. Laboratory blood tests and urinalysis were requested that revealed normal values. Ultrasonography was performed, revealing inflammatory changes with mild free fluid collection in the interloop. The patient underwent an open appendectomy, confirming a normal appendix with omental torsion. Two days later, he was discharged home without postoperative complications. Conclusions In patients with acute abdomen, particularly those with acute appendicitis symptoms, omental torsion should be considered in the differential diagnosis.