ABSTRACT: Hollow axis are widely used in all branches of industry and bear great responsibility. Their behaviour under fatigue being nonetheless well known, and the crack growth phenomenon extensively studied, the understanding of the physical phenomenon somewhat lacks theoretical backing. The present paper gives a start to the theoretical study of the stresses in a hollow axis in flexural mode, considering the variations of its strength moment and its nominal tractive efforts, showing that these endure oscillations harsher than those usually attributed to these cases. Keywords: Fatigue, hollow axis, cracks, bending and rotation, analytical study