Natural killer cells select targets for lysis based on target cell glycoproteins. Compared to controls, K-562 cells treated with kifunensine, an inhibitor of Golgi mannosidase I, accumulate more high mannose-type asparagine-linked oligosaccharide, Man9GlcNAc2, and bind more concanavalin A, an oligomannosyl binding lectin. In addition, natural killer cell lysis of kifunensine-treated cells increases 34% over that of controls. Increased sensitivity to lysis occurs after treatment with other N-glycan processing inhibitors that promote accumulation of high mannose-type glycosides (deoxymannojirimycin and swainsonine). In addition, kifunensine-treated cells form more effector:target conjugates. Monoclonal antibodies to the adhesion molecule LFA-1 and its ligand ICAM-1 reduce lysis of control targets but are less effective in blocking lysis of kifunensine-treated cells. K-562 cells bind anti-ICAM-1 but not anti-LFA-1, and this binding does not change after kifunensine treatment. These data demonstrate conclusively a role for asparagine-linked oligosaccharides in the human natural killer cell:target interaction. The presence of high mannose-type glycans on K-562 cells correlates with increased binding of effectors and a greater susceptibility to lysis. These results support the idea that target cell N-glycosides influence the NK-target interaction mediated by adhesion molecules such as ICAM-1.