We report on 2 different types of left pulmonary artery sling (LPAS), types IA and IIB, diagnosed by fetal magnetic resonance imaging (MRI). We suggest that fetal MRI is an effective tool for accurately diagnosing LPAS and helping guide its perinatal management. Fetal MRI is relatively unaffected by the conditions that limit visualization by echocardiography. When prenatal ultrasound detects either a possible anomalous origin of the left pulmonary artery or a tracheobronchial anomaly, fetal MRI may provide additional information to confirm the LPAS diagnosis and classify its type. To our knowledge, these are the first reports of prenatally diagnosed LPAS by fetal MRI.