We report a case of an abdominal mass in a newborn girl containing a fetus in fetu and two teratomas. Obstetrical sonography revealed the abnormality at 28 weeks of gestation. Post-natal US examination suggested the diagnosis of a fetus in fetu upon the finding of a vertebral column and fetal skeletal bones. US also showed two other rounded masses connected to the main lesion by vascular bundles. Preoperative MRI examination supplied further information regarding tissue composition and vascularisation of the mass lesion. The diagnosis was confirmed by pathological examination. Aetiological factors and radiological diagnosis of this rare tumour are reviewed and discussed.