Congenital abnormalities of the aortic arch arise due to a defect in the unilateral disappearance of arteries of the IVth and exceptionally of the IIIrd primary branchial arches and also of the appropriate sections of paired dorsal aortas. Apart from the cases of complete "situs inversus" and a double aortic arch, the following anatomical possibilities can be distinguished: A--a left-sided aortic arch with a properly established system of branches, B--a left-sided aortic arch with an aberrant right subclavian artery, C--a left-sided aortic arch with a retro-esophageal course and right-sided descending aorta or retro-esophageal course of the brachiocephalic trunk onto the right side, D--a right-sided aortic arch of the "symmetric" type usually coexisting with cyanotic congenital heart lesions, E--a right-sided aortic arch with a retro-esophageal bulge and an aberrant left subclavian artery, and F--a right-sided aortic arch with an aorta descending left-sidedly or brachiocephalic trunk going left-sidedly behind the esophagus. At the Department of Anatomy from 1945 to 1998, 1700 adult cadavers were examined. Throughout this time, one case of each of the types E and C and two cases of the type B were noted in the material. Regardless of the rare occurrence among adults (about 0.01%), the abnormal course of the aortic arch can be the reason for atypical clinical symptoms such as esophageal compression and dysphagia or insufficient cerebral blood supply.