The interaction of halogen atoms with the p(2 x 1)-Ag(1 1 0) surface has been studied by using the pseudopotential total energy method based on density functional theory (DFT). Adsorption properties of halogen atoms at several possible sites on p(2 x 1)-Ag(1 1 0) are presented. Our results show that adsorption energies decrease from F to I. The most stable adsorption site for all halogen atoms is the short bridge (SB) site. The adsorption of halogen can greatly affect both the structural and electronic properties of the surface.