Background: Magnetic resonance imaging (MRI) has become an essential complementary imaging tool during pregnancy. Case Summary: In this case of left-sided congenital diaphragmatic hernia (CDH), fetal cardiac MRI at 29 gestational weeks showed subtle septal bounce and reduced biventricular ejection fraction. On follow-up MRI at 37 gestational week, the right ventricle was significantly dilated (right-to-left ventricle index: 1.9:1.0), indicating increasing right ventricular strain and raising the suspicion of pulmonary hypertension (PH). Post delivery, the newborn required ventilation and circulatory support. Diagnosis of PH was confirmed by echocardiography. After surgical repair, the clinical course was unremarkable. Discussion: This case illustrates that fetal cardiac MRI can provide a prenatal assessment of cardiovascular sequelae of CDH, thereby informing perinatal care. Take-Home Messages: Fetal MRI in CDH is used to accurately quantify fetal lung volume and to detect associated malformations. Additional cardiac assessment can indicate right ventricular strain and should raise suspicion of PH and prompt information of perinatal management.