AbstractThe effect of nerve stimulation was studied on the isolated nerve‐vas deferens preparation from the guinea‐pig suspended in Tyrode solution to which various drugs were added. Azamethonium, hexamethonium, tetraethyl‐ammonium, lobeline and nicotine in ganglionic blocking concentrations inhibited the response to hypogastric nerve stimulation. The block caused by nicotine was generally preceded by a period of potentiation. The other substances produced inhibition without potentiation. The site of action of the ganglionic blocking agents is discussed and it is considered that they may act on 1) a synapse proper 2) chromaffin cells, or 3) “nonspecifically” on the nerve