We discuss the effect of casing wear on squeeze resistance and corrosion life. We analyze methods for prediction of casing wear and propose a new method. Providing that the length of the drill pipe (tool) joint is known, the main factors determining casing wear are the wear factor, the surface kiss (tangential) pressure, and the movement distance, where the contact pressure depends on the kiss pressure and contact arc length. The proposed model describes the experimental data more accurately than other known models.