Throughout their lifetime, fasteners are exposed to a large number of repeated vibrations which cause self-loosening. This situation causes security problem for bolted joints. In this study, novel self-loosening formulations are derived for bolted joints. By using the solution of the differential equation of a tensioned cantilever beam under the lateral tip load and bending moment, transverse displacement distribution along the bolt axis due to the transverse excitation is obtained. Therefore, radial slip amplitudes of the all engaged threads are found by using transverse displacement distribution along the bolt axis. Finally, loosening of bolted joint due to progressive circumferential displacement is discussed. Keywords: Bolted joint, self-loosening