Bypass grafting using autologous vessels or synthetic vascular conduits still has many limitations especially with small-diameter (SD) arteries, thus new approaches to produce alternative vascular grafts are required. Decellularization is a promising solution to produce tissue engineering vascular grafts. Herein, we aimed to test whether decellularized human umbilical artery (dHUA) remains a suitable scaffold for future use in vascular graft bioengineering. Human umbilical artery (HUA) was successfully decellularized as determined by the absence of visible nuclei, and reduction in DNA content, whereas Masson's Trichrome stains and quantitative proteomics showed preservation of the extracellular matrix components. Moreover, elimination of MHC class I and II in dHUA was verified by immunohistochemistry, and mechanical testing demonstrated no differences regarding ultimate tensile strength and suture retention strength between decellularized and native HUA. Human umbilical cord vascular endothelial cells (HUVECs) attached and grew well within the dHUA while maintained in a perfusion 3D-bioreactor, confirming dHUA cytocompatibility. Finally, in vivo implantation in sheep carotid bypass model confirmed that dHUA withstood arterial blood pressure in vivo with successful anastomosis. Sheep host immune blood cell count showed no obvious difference between dHUA and allogeneic sheep decellularized vessel. Yet, ultrasound examination and end-point histology, confirmed as expected that dHUA is prone to early (