The molecular dynamics simulation technique has been applied to study the effects of temperature on Ni and Al with point and planar defects. For this purpose a well established program 'dyn86' containing the DYNAMO subroutine has been used. Semi-empirical potentials based on the embedded atom method (EAM) have been employed to calculate the lattice parameter and energy per atom in order to determine the melting point. The effects of point defects, including self, substitution, and interstitial, on the melting point have been investigated. The twin formation energy of some low index (111), (112), (113), and (114) twin-interfaces and their effects on the melting point of Ni and Al are also studied. It is observed that the presence of defects (point or planar) lowers the melting point of metals, as compared to the simulated melting point of a defect-free crystal.