Abstract: A number of carbamates useful as insectisides have attracted much attention owing to their marked physiological activity. Both phenyl, naphthyl N,N-dimethylcarbamates as well as their mono- and dichloro-analogues were prepared in the present work in order to study the relationship between chemical constitution and insecticidal activity. Preliminary tests showed that dichloro-phenyl N,N-dimetnylcarbamate possessed strong insecticidal activity against house-flies, naphthyl N,N-dimethylcarbamate displayed strong insecticidal activities both to house-flies and mosquito-larvae whilst monochloronaphthyl N,N-dimethylcarbamate was more active to mosquito-larvae than to house-flies. Toxicity tests against 'mammalians are in progress.