Primary cardiac tumor is uncommon in childhood, with an incidence of 0.06-0.32%, and intrapericardial teratoma represents an exceptional rarity among these entities. Germ cell tumors (GCT) are rare, representing only 1-3% of childhood tumors. Twenty per cent of GCT are malignant and are associated with age and location. Extragonadal involvement accounts for nearly half of the cases. Anterior mediastinum is a common location of malignant germ cell tumors, yet pericardial and aortic adventitia involvement have been rarely reported. Here we report the case of a preterm twin baby boy with intrapericardial mixed germ cell tumor who presented with hydrops fetalis and pericardial effusion.