False cysts have no cellular lining and usually originate from past abdominal trauma. We herein report a 23-year-old woman with an asymptomatic splenic false cyst. She had no history of abdominal trauma. Abdominal computed tomography showed a cystic lesion without internal structure. In contrast, magnetic resonance imaging and ultrasonography revealed an inhomogeneous internal structure without fluid/debris level. Although the images were not typical of a splenic false cyst, the surgically excised mass histologically showed a splenic false cyst (no epithelial element). Non-traumatic splenic false cysts are rare and show nonspecific clinical findings and symptoms. The recommended treatment is splenectomy.