The electron gas model for the lattice dynamics of cubic metals propounded by one of us earlier has been used to test Lindemann's melting criterion by calculating the ratio γm of the mean-square amplitude of thermal vibrations to the square of the interatomic spacing at the melting point for a number of cubic metals belonging to different groups of the periodic table. The calculated γm has roughly the same value for elements belonging to one particular group, but the spread in γm values is quite large from one group to another. It is concluded that Lindemann's hypothesis of constant γm for all solids is inadequate.