Several pairs of aryl esters of stereoisomeric amino alcohols in the 2-dimethylaminocyclohexanol and tropine series have been studied with respect to their blocking actions against the viable single node of Ranvier in frog sciatic nerve, against the in vitro acetylcholinesterase-acetylcholine system, and in part as convulsant agents in small laboratory animals. In the 0.1–1.0 m M concentration range and at pH 7.5, the esters are very powerful in blockade of nodal excitability and elevation of threshold voltage requirement of the node. These blocking actions are quite stereospecific in the sense of cis vs. trans and tropine vs. ψ-tropine configurations of the small adduct molecules. On the esterase system, these same cyclic derivatives function as weak-to-moderate inhibitors with a considerable degree of stereospecificity in their actions, but the specificity pattern on esterase response does not conform to that displayed by the node. Stereospecificity in convulsant response to this series of esters also carries over to relative toxicities in intact animals.