Within a period of 5 years, we encountered three patients with a small rectus sheath hematoma, presenting with clinical signs of appendicitis. The rectus sheath hematoma was diagnosed by ultrasound (US) in all three cases and confirmed by computed tomography (CT) in two. None of the hematomas was palpable and in two of three cases in which the patient did not receive anticoagulant therapy. In patients who are sonographically examined for suspected appendicitis, the abdominal wall should be studied as well, to exclude a nonpalpable rectus sheath hematoma. In cases in which a hematoma is found, an unnecessary appendectomy can be prevented.