In this paper we report comparisons between theoretical and experimental values of the velocity of sound in twenty liquid simple metals near the melting point. We used three model theories, namely, (1) an improved Rosenfeld’s approach, (2) Ascarelli’s approach and (3) a modified Ascarelli’s approach. For alkali metals, the three model theories give much the same predictions in the velocity of sound. For polyvalent metals, electrons play an important role when the valency is increased. For noble metals, the degree of agreement between theory and experiment is improved by taking into account the effects of the ionic core due to the s-d hybridization.