Three patients with coarctation of the abdominal aorta who were observed in an 8-year period illustrate some of the problems in diagnosis and management of this lesion. Coarctation was located at the level of the renal arteries in two instances, and above the renal vessels in the third. Bypass graft resulted in significant improvement in one patient. The second patient is presently asymptomatic with only mild systemic hypertension. A promotion thrombosis complicated the clinical course of the third infant and contributed to her early death. Histologic examination of the aortic wall revealed a unique pattern of fibromuscular dysplasia in this patient. Sixty-nine additional instances of this malformation have been reported in children. On the basis of this review, coarctation of the abdominal aorta may be classified into segmental and hypoplastic types. Renal arterial abnormalities are frequently associated. Physical examination reveals systolic murmurs and thrills in the epigastric and lumbar areas. Roentgenographic studies demonstrate a normal aortic arch and absence of rib notching. The atypical location of the coarctation is confirmed by abdominal aortography. The primary factor affecting ultimate prognosis is the presence of associated renal artery pathology. Operative procedures must include repair or bypass of significant renal arterial abnormalities.