Gears in service conditions experience inevitable tooth damage. These damages can cause changes in the time-varying mesh stiffness depending on the mode of damage. The time-varying mesh stiffness of gears is an essential input in calculating gear dynamic responses. Several researchers have evaluated the mesh stiffness of gear teeth with single-mode damage like pitting, spalling, root cracks and wear using either or any combination of analytical, numeric and experimental models. However, limited research has been done on investigating the mesh stiffness of gear teeth undergoing multi-mode damage. In this work, an analytical model is proposed to evaluate the mesh stiffness of a tooth on the pinion with single-mode damage, including pitting, spalling, and surface crack, separately. In addition, a gear tooth with a combination of pits, spalling and surface cracks is also evaluated. The volume of damage on the tooth is kept constant to provide a basis for comparison. The comparison highlights the possible effects of the combined damage modes, which is a more realistic occurrence in gears in service.