This article is dedicated to such a congenital anomaly of human development as an accessory spleen. In our article we discuss the main causes of its occurrence, indicate the most frequent localizations, discuss the complexity of diagnosis, and demonstrate the modern possibilities of medical imaging in differential diagnosis of this pathology with other neoplasms of the abdominal cavity. Moreover, we present a clinical case of an accessory spleen located in an atypical place — in the liver gates, which is a rare finding. The article is illustrated with original computed tomography, magnetic resonance imaging, and radionuclide studies scans.