PurposeThe purpose of this work was to assess the impact of respiratory motion and to compare methods for suppression of respiratory motion artifacts in 4D Flow MRI.MethodsA numerical 3D aorta phantom was designed based on an aorta velocity field obtained by computational fluid mechanics. Motion‐distorted 4D Flow MRI measurements were simulated and several different motion‐suppression techniques were evaluated: Gating with fixed acceptance window size, gating with different window sizes in inner and outer k‐space, and k‐space reordering. Additionally, different spatial resolutions were simulated.ResultsRespiratory motion reduced the image quality. All motion‐suppression techniques improved the data quality. Flow rate errors of up to 30% without gating could be reduced to less than 2.5% with the most successful motion suppression methods. Weighted gating and gating combined with k‐space reordering were advantageous compared with conventional fixed‐window gating. Spatial resolutions finer than the amount of accepted motion did not lead to improved results.ConclusionRespiratory motion affects 4D Flow MRI data. Several different motion suppression techniques exist that are capable of reducing the errors associated with respiratory motion. Spatial resolutions finer than the degree of accepted respiratory motion do not result in improved data quality. Magn Reson Med 78:1877–1882, 2017. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution Non‐Commercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.