Whole-organ decellularization has opened the gates to the creation of 3D extracellular matrix (ECM) templates that mimic nature's design to a degree that-as for today-is not reproducible with any synthetic materials. Here, we describe a whole-heart decellularization approach through software-controlled automated coronary perfusion with standard decellularization detergents, enabling us to create native ECM-derived 3D templates that preserve the basic anatomy, vascular network, and critical ECM characteristics of the native heart. Such a cardiac ECM platform directly derived from nature itself might help us to better understand and reproduce cardiac biology and may even lay the grounds for the construction of a bioartificial heart in the future.