Nearly 90% of failures in mechanical components are attributed to cyclic loading and stress which result in fatigue damage. In this book, a fatigue life assessment of a diesel engine pump part is addressed. A finite element analysis of the component for each types of ductile cast irons(GGG- 40, GGG-50 and GGG-60) is performed. Consequently,the elastic and plastic stress concentration factors for each materials are obtained. Neuber''s rule is then used for determination of cyclic stress and strain at the component''s notch which is the critical point for crack initiation and propagation. Experimental tests involving component specimen loading at R=0 was conducted to verify the accuracy of fatigue life prediction. The procedures used in this book help shed some light in design and analysis of mechanical components for fatigue and should be specially useful for professionals and students working in this critical topic.