We tested classically used organic nitrovasodilators such as s-nitroso-n-acetyl-D,L-penicillamine, 3-morpholino-sydnonimine, pentaerythrityl-tetranitrate, isosorbide-dinitrate, isosorbide-mononitrate, glyceryl-trinitrate on different isolated conductive arterial and venous blood vessels of the same species (rabbit). We found an up to two orders of magnitude more pronounced venoselectivety in the systemic-circulation as compared to the lung-circulation. ISMN and PETN were most venoselective nitrovasodilators, with PETN being the most potent drug in all vessels studied.