Crossed pulmonary arteries (CPAs) are a rare abnormality in which the ostium of the left pulmonary artery originates superior to the right pulmonary artery and to its right. Recognition of this rare pathology is important because it generally is accompanied by other congenital heart defects, extracardiac anomalies, and certain genetic problems. To date, only a few cases have been reported, and most of these cases have been associated with complex cardiac abnormalities. The authors detected 20 cases of CPA between June 2009 and November 2012 through their increasing awareness of this anomaly. Approximately 9,250 echocardiograms were performed during this period, and all of them also were checked for this anomaly. This report describes 20 cases of this CPA, with an emphasis on the clinical features and the genetic and cardiac abnormalities. The patients ranged in age from 1 day to 13 years at the time of the initial diagnosis. Four patients had complex cardiac pathologies such as tetralogy of Fallot, truncus arteriosus, transposition of the great arteries, and complete atrioventricular septal defect. Of the 20 patients, 11 had ventricular septal defects, and 12 had atrial septal defects. Pulmonary artery stenosis was detected in 12 (55 %) of the 20 patients. Aortic arch abnormalities such as interrupted aortic arch, right aortic arch, and coarctation of the aorta were detected in six patients. One patient had a left persistent superior vena cava. In 45 % of the cases, an associated genetic syndrome (DiGeorge-, Noonan-, Holt-Oram syndromes, vertebral, anal, cardiac, tracheal, esophageal, renal, limb anomalies [VACTERL] anomalies) was present. These syndromes were diagnosed based on their clinical features. Karyotype and fluorescent in situ hybridization (FISH) analyses for a 22q11 deletion were performed for 11 patients, with 10 patients found to have normal karyotype and FISH results. Only one patient had a 22q11 deletion. Six patients underwent successful operations. During the follow-up period, 3 of the 20 patients died. At this writing, the remaining patients are clinically stable and being followed without surgery. The authors believe that CPA is not a rare anomaly. If careful echocardiographic examination is performed, CPA will be diagnosed more frequently. Although this pathology usually is associated with genetic syndromes and other cardiac abnormalities, patients with CPA generally are asymptomatic.