The effects of the following vasoactive drugs: Bencyclan fumarate, Cetiedil citrate, Cinepazide maleate, Dihydroergocristine methane sulphonate, Nafthydrofuril acid oxalate, Papaverine hydrochloride, Piribedil monomethane sulphonate, Raubasine, Thymoxamine hydrochloride and Xanthinol nicotinate, in concentrations ranging between 0.001 - 2 mM, were tested on the compound action potentials led off from human isolated sympathetic ganglions. The experiments, carried out on 50 isolated lumbar ganglion preparations removed from 23 subjects with arteriopathy of the limbs, indicated that all the drugs are able to impair the synaptic transmission, although at different concentrations. These findings are in favour of the hypothesis that the vasodilatatory effects observed after therapeutic treatment of patients with vasoactive drugs are partially produced by the vasodilatation following the depression of the sympathetic nervous transmission.