<p>This study aimed to compare computational fluid dynamics (CFD) results to those acquired in vivo with 4D Flow magnetic resonance imaging (MRI) and in vitro with a 3D printed model using pressure catheter manometry. The goal was to investigate the haemodynamics of the cerebral venous system (CVS) and assess the accuracy of the methodologies, to highlight any discrepancies between the&#xa0;techniques. One participant living with multiple sclerosis (MS) and one healthy control were recruited for this study. MRI was performed to generate 3D geometries of the anatomy and to compute blood flow rates at the boundaries, with 4D Flow MRI velocity streamlines for the control participant. CFD models were created for the two participants and simulated using the patient-specific boundary conditions. A 3D printed geometry of the MS participant was created and a flow loop experiment was conducted to measure the cerebral venous pressures. The venous pressures were found to be comparable to that observed in the CFD simulation. 4D Flow MRI velocity streamlines of the CVS were found to correspond well to the CFD findings, except for a few regions, which were likely impacted by the low resolution of the MRI. The use of all three methods enabled the successful validation of the velocity, flow features and pressure, and ensured that the haemodynamics of the CVS as resolved using CFD, were accurate. This highlights the potential for increased efficacy of the clinical outcomes of future studies that utilise such methods.</p> Graphical abstract <p></p>