Before introduction into clinical routine 4D Flow MRI has to be tested in larger scale studies. For data to meet quality standards for these studies various potential error sources have to be addressed. The aim of this study was to provide a comprehensive inter-scanner, inter-vendor, inter-individual cross-over evaluation of a 4D Flow sequence. The thoracic aorta of eight volunteers was examined on two 3T MRI-Scanners of different vendors and analyzed by two readers using three different software. While there was no significant difference between readers and MRI scanners, differences between analysis-software where beyond clinically acceptable limits.