Three-dimensional (3D) images of casting defects present in broken and nonbroken fatigue samples of a cast Al alloy (A380–ISO: AlSi8Cu3Fe) have been obtained using laboratory X-ray tomography. The 3D images have been processed to obtain various parameters (size, distance from the surface, projected area, etc.), for all the defects present in the gage length. 3D finite element meshes have also been generated from the tomographic images in order to compute the stress field at the vicinity of each defect. Correlations between the fatigue properties of the investigated samples and the above mentioned parameters are analyzed in order to elucidate which one seem to be predominant for the studied material.