Several dithiocarbamates were synthesized and their herbicidal activities to radish and barnyardgrass were examined. Some benzyl N, N-dialkyldithiocarbamates such as N-methyl-N-ethyl-, N-methyl-N-n-propyl-, N, N-diethyl- and N, N-diisopropyl-dithiocarbamates showed high activity to these plants, but N-monoalkyl-, N, N-diaryl- and N, N-diaralkyl-dithio- carbamates were not so active. Some substituted benzyl N, N-dialkyldithiocarbamates such as 4-dimethylaminobenzyl N-methyl-N-ethyldithiocarbamate and 4-methoxybenzyl N, N-diethyldithiocarbamate showed high activity to broad-leaved plants. Substituted benzyl N, N-dialkyldithiocarbamates except 4-cyanobenzyl N, N-diisopropyldithiocarbamate, however, were less active to graminaceous plants.