Two series of new alkylaminoacylamino-1,2-benzisothiazoles were synthetized and assayed for anesthetic activity. The above-mentioned compounds were prepared by reaction between the appropriate amines and 3-(haloacyl)amino-1,2-benzisothiazoles, which had been obtained by acylation of a 3-amino-1,2-benzisothiazole with the required haloacylchloride. The local anesthetic activity of the compounds, isolated as hydrochlorides, was tested for surface, infiltration and trunkular anesthesia. Several compounds proved to be active in infiltration and trunkular anesthesia, whereas no compound showed local surface anesthesia. On the basis of the results obtained the structure-activity relationships were examined.