Gray cast iron that is used for automobile engine cylinder liners was laser surface hardened using Nd∶YAG quasi-continuous and CO_2 continuous wave laser, respectively. The macromorphology and microstructure of the laser surface hardened layers were investigated using an optical microscope. Geometric dimensions including depth and width and microhardness distribution of the hardened layers were also examined in order to evaluate the quality of the hardened layers. Gray cast iron that is used for automobile engine cylinder liners was laser surface hardened using Nd: YAG quasi-continuous and CO_2 continuous wave laser, respectively. The macromorphology and microstructure of the laser surface hardened layers were investigated using an optical microscope. depth and width and microhardness distribution of the hardened layers were also examined in order to evaluate the quality of the hardened layers.