Neonatal aortic dissection is rare and most frequently iatrogenic. Decision making and appropriate imaging are highly challenging for pediatric cardiologists and radiologists. We present MRI and echocardiographic findings in the follow-up at 6 months of age of a boy with a conservatively treated iatrogenic neonatal aortic dissection (type B). To evaluate the morphology of the aortic arch and descending aorta, we carried out multidirectional time-resolved three-dimensional flow-analysis and contrast-enhanced MR angiography (CE-MRA). The MRI and Doppler echocardiographic results were closely comparable. Three-dimensional visualization helped assess details of blood flow acceleration and alteration caused by the dissection, and played a key role in our deciding not to treat surgically.