Vestipitant, also known as GW597599, is a neurokinin1 receptor antagonist that was being developed by GlaxoSmithKline for the treatment of postoperative nausea and vomiting. Vestipitant is one of the most potent and selective NK(1) receptor antagonists ever discovered, showing appropriate pharmacokinetic properties and in vivo activity. Its actions support the utility of NK(1) receptor blockade in the alleviation of anxiety and, possibly, depression. It was under development as a potential antiemetic and anxiolytic drug, and as a treatment for tinnitus and insomnia. Vestipitant was shown to improve sleep maintenance in patients with primary insomnia, with no associated next-day cognitive impairment. The effects on wake after sleep onset and total sleep time were maintained following repeated dosing. Vestipitant has anxiolytic properties and a good safety profile. Vestipitant was investigated for potential effect against chronic tinnitus as a stand-alone treatment and in conjunction with a selective serotonin reuptake inhibitor, paroxetine. Although well-tolerated vestipitant, alone or in combination with paroxetine, was not effective in ameliorating tinnitus in this patient group.