Chlorsulfuron was applied to annual bluegrass (Poa annua L.), creeping bentgrass (Agrostis palustris Huds ‘Penncross’), hard fescue (Festuca ovina var. duriuscula Koch ‘Scladis’), tall fescue (Festuca arundinacea Schreb ‘Kentucky 31’), quackgrass (Agropyron repens L. Beauv), smooth bromegrass (Bromus inermis Leyss), and perennial ryegrass (Lolium perenne L. ‘Crown’) at the rates of 0, 141, and 282 g a.i.·ha−1 in repeated greenhouse experiments. Tall fescue and perennial ryegrass were very sensitive to the chlorsulfuron in both experiments. Creeping bentgrass, hard fescue, quackgrass, and smooth bromegrass were more tolerant of chlorsulfuron treatments than the sensitive species. Annual bluegrass was damaged by chlorsulfuron in the first experiment, but not in the 2nd. Chemical name used: 2-chloro-N-[[(4-methoxy-6-methyl-l, 3, 5,-triazin-2-yl)amino]carbonyl]benzene sulfonamide (chlorsulfuron).