Spontaneous rupture of the ureter is rare and usually associated with calculous diseases. The presentation may mimic other more common causes of acute abdomen, such as acute appendicitis and diverticulitis. Although urinary tract symptoms and abnormal urinalysis findings are the usual telltale signs of urological disorders, these clinical manifestations may be atypical or absent in ureteral rupture. We report two patients with spontaneous ureteral rupture who presented to our emergency department with right lower quadrant abdominal pain without urinary tract symptoms, and were initially misdiagnosed with acute appendicitis. The final diagnosis in both cases was confirmed by contrast extravasation from the ureter on computed tomographic scans.