During pre-harvest of corn seeds, produced by high temperature and excessive moisture content, it can appcar stress cracks. This cracks are internal with difficult detection. Some techniques like LTSEM, dye uses, x-ray and microtomograph analysis severe used in characterization and investigation of the cracks and this effects in seed corn quality. The cracks are often along the embryo axis, but they are also detected in others positions, irrespective of the shape of the kernel. Dyes were not useful to identify this kind of crack because they did not extend into the pericarp. X-ray analysis enables visualization of stress cracks that are not visible to the human and, therefore, gives a better estimate of the percentage of cracks. However, low temperature scanning electron microscopy of the surface of milled kernels and x-ray microtomograph analysis reveals cracks that are unnoticeable by visual or usual x-ray inspection. The seeds tested had a crack of some sort in the endosperm tissue but these cracks developed following the houndary of the starch granules. The internal stress cracks generally were not detrimental to germination and vigor, except when they were localized inside or perpendicular to the embryo axis, probably by impeding nutrient translocation to the embryo, during germination process.