Undifferentiated embryonal sarcoma (UES) is an uncommon paediatric hepatic tumour that clinically simulates a liver abscess when present with fever. This report describes a case of UES in a 12-year-old boy, who presented with abdominal pain, swelling and fever, all simulating a liver abscess. The possibility of UES was considered at imaging, based on the solid appearance on ultrasound and cystic appearance with serpiginous peripheral vessels on computed tomography/magnetic resonance imaging. The diagnosis was confirmed at histopathology.