(±)-Nornicotine-d4 is intended for use as an internal standard for the quantification of (±)-nornicotine by GC- or LC-MS. (±)-Nornicotine is an active metabolite of nicotine and a nicotinic acetylcholine receptor (nAChR) agonist. It induces currents in Xenopus oocytes expressing human α7 nAChRs or α6 subunit-containing nAChRs (EC50s = 17 and 3.7 µM, respectively). (±)-Nornicotine promotes cell migration and destabilizes cell-cell junctions in EA.hy926 endothelial cells. It is self-administered in rats.