The free vibration of a general elastically restrained symmetric nonuniform Timoshenko beam resting on a nonuniform elastic foundation and subjected to axial loads is studied. The relation between the flexural displacement and the angle of rotation due to bending is derived. The two coupled governing characteristic differential equations are reduced into one complete fourth-order ordinary differential equation with variable coefficients in the angle of rotation due to bending. The frequency equation is expressed in terms of the four normalized fundamental solutions of the differential equation. If the closed form fundamental solutions of the governing characteristic differential equation are not available, then the approximate fundamental solutions can be obtained through a simple and efficient algorithm. The limiting cases such as uniform Timoshenko beams, nonuniform Rayleigh and Bernoulli-Euler beams are examined. Several examples are given to illustrate the validity and accuracy of the analysis.