In this paper, the linear vibrations of thermally prestressed beams are studied, including the prebending effects. General equations governing structural vibrations superimposed on an initial static state are first given. They are applied to a planar Euler-Bernoulli beam under the assumption of small prestrain and large predisplacement. Initial imperfections are included in the whole analysis. The governing equilibrium equations are solved using a finite element method. This model is then validated through experiments inside a climatic chamber.