The effect of self-nucleation on the crystallization and melting behavior of isotactic polypropylene (i-PP) and low ethylene content propylene-ethylene copolymers were investigated. Isothermal crystallization kinetics were studied using the Avrami equation and Lauritzen-Hoffman nucleation theory. It was found that self-nucleation can enhance the crystallization. The surface free energy sigma(e) decreased for the self-nucleated sample. The melting behavior was affected by the preselected temperature, T-s, at which the polymer was partially melted.