Mirror syndrome, also called Ballantyne syndrome, is a rare condition in pregnancy, defined by the presence of the clinical triad of fetal hydrops, placentomegaly and maternal oedema. Any aetiology of fetal hydrops, including rhesus iso-immunization, congenital infection, twin-to-twin transfusion, structural anomalies and fetal malignancies, can lead to the syndrome. The pathogenesis, although not well established, mimics trophoblastic damage and maternal vascular endothelial dysfunction, as is also seen in pre-eclampsia, and, hence, the two conditions may have a similar clinical presentation. They may even co-exist, where a patient with maternal mirror syndrome develops features of pre-eclampsia. A timely, accurate diagnosis and prompt interventions are needed to prevent fetal mortality and maternal morbidity.