Herbicide resistance raises the possibility that the agricultural industry and crop producers might loose a valuable chemical tool that is essential for the control of weeds in wheat (Triticum aestivumL.) production. The recognition of herbicide resistance occurred relatively recently (1960), despite the widespread use of selective herbicides worldwide. Resistant biotypes ofAverta fatuaL. to diclofop-methyl (±)2-[4-(2,4dichlorophenoxy)phenoxy]propanoic acid were confirmed in the western Cape. Recently, farmers and chemical companies reported resistance ofLoliumspp. to several selective herbicides in small grains in the western Cape. The main objective of the present study was to assess resistance ofLoliumspp. against ACC-ase inhibitors used in wheat production. Seed ofLoliumspp. which were suspected to be resistant was sown in pots in a glasshouse at a temperature regime of 15°C/20°C (night/day). During the 2–4-leaf stage, the plants were sprayed with four herbicides viz. diclofop-methyl, clodinafop-propargyl (2-propynyl (R)2-[4-(5-chloro-3-fluoro-2-pyridinyloxy)-phenoxy-pro pionate], tralkoxydim (2-(1 [ethoxyimo)propyl]-3-ktydroxy-5-(2,4,6-trimethylphenyl)cyclohex-2-enome) and imazamox, 2[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-(methoxymethyl)-3pyridinecar bolic acid at double the registered rates. Four weeks after herbicide application, percentage control was measured by comparing fresh plant mass. This study confirmed resistance ofLoliumspp. to ACC-ase inhibitor graminicides registered for use in wheat in the western Cape.