A new methodology of fatigue life prediction for corroded specimens is proposed in this paper based on an equivalent initial flaw size (EIFS) methodology and a corrosion pit growth function. The proposed EIFS methodology is based on the Kitagawa diagram and the El Haddad model. Life prediction for smooth specimens is performed by employing the crack growth analysis starting from an assumed crack size determined by the EIFS. A growing semi-circular notch is assumed to exist on the specimen surface caused by the corrosive environments. An asymptotic solution is used for the stress intensity factor solution of a crack at the notch root. Fatigue life can be predicted using the crack growth analysis, in which a crack propagates from the notch root. Various experimental data for aluminum alloys and steels are used to validate the proposed methodology.