This chapter reviews 20 years of studies on the vestibular deficit in Spinocerebellar Ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), and briefly discusses bilateral vestibulopathy as the initial manifestation of CANVAS (Cerebellar Ataxia with Neuropathy and Vestibular Areflexia Syndrome). Following a brief introduction on SCA3/MJD, the review will cover the following topics: the Vestibulo-Ocular Reflex (VOR) deficit in SCA3/MJD as part of the disease phenotype; the probable central vestibular degeneration that may account for this deficit; the potential use of horizontal VOR gain as a reliable neurophysiological biomarker of the disease; the hidden vestibular symptomatology of SCA3/MJD; and the impairment of mentalizing functions in patients with SCA3/MJD. The relevance of these findings for the diagnosis and management of SCA3/MJD patients, along with their potential application in future therapeutic trials, will be emphasized. This will be followed by a brief note on CANVAS. Given that those studies started when I examined patients with SCA3/MJD who surprisingly had an impaired bedside Head Impulse Test (HIT), a clinical test originally described as a sign of canal paresis, and never reported at that time in central disorders, I will highlight the importance of this simple and precise test.