Additive manufactured IN718 has a complex microstructure that cannot be fully described using two-dimension material characterization methods. The as-built microstructure is basically composed of elongated grains, approximately 300μm in the building direction, mixed with smaller and more equiaxed grains (equivalent diameter around 30μm), a high number of twins and porosity. Therefore, there is an imperious need to carry out a three-dimensional characterization that allows a better understanding of the microstructure evolutions, such as grain growth during thermal treatment following the building step. In this study, an as-built additive manufactured IN718 is characterized in 3D. The mechanical serial-sectioning procedure, where vibratory polishing and electron backscattered diffraction (EBSD) analyses were sequentially performed, is presented. The resulting three-dimensional volume, reconstructed using Dream3D, is then immersed in a finite element level-set framework and grain growth simulations that consider anisotropic grain boundary energy and mobility are carried out.