Chemical resolution of (plus or minus)-mecamylamine Merck could not be accomplished by the published procedure, but succeeded with optically active R-(+)-alpha-methylbenzylisocyanate affording diastereomeric urea derivatives separated column chromatography. Alkaline hydrolysis of these ureas afforded (+)- and (-)-mecamylamine. The hydrochlorides of the antipodes showed the expected optical rotations and are being evaluated in assays measuring binding to subunits of the nicotinic acetylcholine receptor.