Herbicidal-substituted .alpha.-(trimethylcycloalkenyl)-N-alkylacetamides of the formula ##STR1## wherein R is a linear or branched alkyl or alkoxyalkyl radical with 1-6 carbon atoms or an allyl radical, optionally substituted with C.sub.1 -C.sub.4 alkylene groups, and X is a substituent from the group consisting of hydrogen, methyl, chlorine and bromine, in any combination, the free valences signify hydrogen and two of the methyl groups on the ring are attached to the same carbon atom, are useful pre- and post-emergent herbicides for weed control in crops.