The placenta functions to nourish and protect the fetus. Imaging of the placenta can have a profound impact on patient management, owing to the morbidity and mortality associated with various placental conditions. To fully appreciate placental pathology, its physiology, anatomy, and variant anatomy will be outlined. Placental conditions affecting the mother and fetus include molar pregnancies, placental hematoma, abruption, previa, accreta, vasa previa, choriocarcinoma, and retained products of conception. Ultrasonography remains the definitive modality in diagnosing most of these conditions, with magnetic resonance imaging remaining an adjunctive measure. Computed tomography is occasionally used in cases of trauma and tumor staging. Copyright © 2012 Elsevier Inc. All rights reserved.