Coarctation of the aorta is a congenital cardiovascular defect that causes a constriction in the descending thoracic aorta. It is poorly understood why certain problems exist after corrective surgery. It is hypothesized that these problems are a result of shear rate changes that occur as an effect of the coarctation. To gain a better understanding of the cause of certain post-surgical coarctation problems, a compliant in vitro model of the aortic arch and descending aorta with a coarctation was constructed from silicone elastomer. Stereoscopic Particle Image Velocimetry (PIV) was used to obtain 3D velocity maps of the flow upstream of the coarctation, downstream of the coarctation, and at the coarctation. Results show that the coarctation causes a high speed turbulent jet to form at the exit of the coarctation. The jet is directed towards the medial wall by the coarctation and induces flow reversal at the lateral wall. Shear rate values are significantly above the normal in vivo values at the medial wall and lateral wall shear rates are of the same magnitude as in vivo values but in the negative direction. The turbulent nature of the flow causes the areas of reattachment at the lateral wall to fluctuate creating an oscillatory shear at the lateral wall.