4D-flow sequences on two 1.5T scanners from different vendors (Philips Achieva dStream and Siemens MAGNETOM Aera) were validated head-to-head. 4D-flow in a pulsatile flow phantom showed high accuracy and precision compared to reference laser particle image velocimetry for both scanners. 2D-flows in ascending and descending aorta and pulmonary trunk were compared to 57 4D-flow scans in 10 subjects. Lower bias for flow volumes was found on Aera (-4.7±12.5%) compared to Achieva (-18.0±20.1%). Kinetic energy showed lower bias for repeated examinations at the same scanner compared to different scanners the same day. 4D-flow without respiratory gating on Aera showed acceptable quality.