Among 34 patients with vascular rings, symptoms of tracheal and esophageal compression or both occurred during the first six months of life in 24 (71%). Diagnosis was made in all cases on either plain x-ray film or esophagogram, and was confirmed by operation or angiogram. Associated defects were numerous, with ventricular septal defect (5) and Down's syndrome (3) most common. Operative intervention was required in 18 cases (53%), including 12 of the 14 double arches. Only one of the ten patients with symptomatic recurrent subclavian artery underwent operation. Fourteen of the 18 patients operated upon had early total relief of symptoms, and 17 had excellent late results. A simple system for describing the embryology of vascular rings is presented, and the embryologic relationship between vascular rings and interrupted aortic arches is described. Because of frequent delay in recognition of vascular rings and other surgically correctable lesions, the work-up of every child with two or more episodes of pneumonia should include barium swallow.