The main purpose of this study is to present both the fundamental and some higher natural frequencies of Timoshenko beams on the Pasternak foundations, that is, an elastic foundations with shear layer. The ordinary differential equation governing the free vibrations of this beam is derived as nondimensional forms. The Runge-Kutta method and Determinant Search method, respectively, are used to perform the integration of the differential equation and to determine the natural frequencies. Hinged-hinged, hinged-clamped and clamped-clamped end constraints are applied in numerical results. As the numerical results, the lowest four nondimensional frequency paramters are shown as functions of three system parameters: the shear foundation parameter $g_0$, the slenderness ratio s, and the Winkler foundation parameter ${lambda}$. In addition, the effect of ${Gamma}(={alpha}E/G)$ on the frequencies is investigated.