PCT No. PCT/EP96/03996 Sec. 371 Date Feb. 17, 1998 Sec. 102(e) Date Feb. 17, 1998 PCT Filed Sep. 12, 1996 PCT Pub. No. WO97/10714 PCT Pub. Date Mar. 27, 1997A composition comprising at least one sulfonylurea of the formula I wherein R1 is substituted alkyl; halogen; a group ER6 (E=O, S or NR7); COOR8; NO2; S(O)oR9; SO2NR10R11; or CONR10R11; R2 is hydrogen, alkyl, alkenyl, alkynyl, halogen, alkoxy, haloalkoxy, haloalkyl, alkylsulfonyl, nitro, cyano or alkylthio; R3 is F, CF3, CF2Cl, CF2H, OCF3, OCF2Cl, or, if R1 is CO2CH3 and R2 is simultaneously fluorine, R3 is Cl, or, if R1 is CH2CF3 or CF2CF3, R3 is methyl, or, if R4 is OCF3 or OCF2Cl, R3 is OCF2H or OCF2Br; R4 is alkoxy, alkyl, alkylthio, alkylamino, dialkylamino, halogen, haloalkyl or haloalkoxy; and R5 is hydrogen, alkoxy or alkyl; or an enviromentally compatible salt of I, and an aryloxyalkanoic acid selected from the group consisting of 2,4-D, 2,4-DB, clomeprop, dichlorprop, dichlorprop-P, dichlorprop-P (2,4-DP-P), fenoprop (2,4,5-TP), fluoroxypyr, MCPA, MCPB, mecoprop, mecoprop-P, napropamide, napropanilide, triclopyr, and an enviromentally compatible salt thereof exhibits a synergistic herbicidal effect.