It is generally believed that balloon angioplasty of diffuse, long-segment aortic coarctation is not effective. In this report, we describe two neonates with diffuse, long-segment coarctation in association with complex congenital heart defects in whom we were successful in effectively treating coarctation with transumbilical artery balloon angioplasty. Based on this experience, it may be concluded that balloon angioplasty of long-segment coarctation in neonates is feasible and effective, but confirmation in a larger group of patients may be necessary prior to general adoption of this concept.