Purpose <p>The primary endpoint was to determine the prevalence of vestibular hypofunction in patients suffering from obstructive sleep apnea (OSA). Secondary and tertiary objectives were to determine any correlation between vestibular hypofunction and the degree of sleep apnea and/or the Dizziness Handicap Inventory (DHI) scores, and the presence of comorbidities, respectively.</p> Methods <p>A cross-sectional prospective cohort design in which 175 adult subjects diagnosed with either probable, mild, moderate, or severe OSA were recruited. Subjects underwent complete video head impulse (vHIT) testing and a self-reported fulfilment of the DHI questionnaire. A standardized approach was applied for the interpretation and classification of the vHIT results.</p> Results <p>The prevalence of vestibular hypofunction was found to be 6.9%. No significant differences in apnea-hypopnea-index (AHI) score (<i>p</i> = 0.26) or within AHI groups (<i>p</i> = 0.45) were found. Consistently, no significant differences in total DHI score (<i>p</i> = 0.14) or within DHI subcategories (<i>p</i> = 0.21) were found. OSA and an accompanying heart condition was significantly correlated to having vestibular hypofunction (<i>p</i> = 0.00). Subjects with vestibular hypofunction had a significantly higher number of comorbidities (<i>p</i> = 0.03). Furthermore, the probability of having vestibular hypofunction significantly increased with increasing numbers of accompanying comorbidities (<i>p</i> = 0.03).</p> Conclusion <p>Twelve subjects (6.9%) in a population of adult OSA patients had vestibular hypofunction. No correlation between the prevalence of vestibular hypofunction and the degree of OSA was found. Consistently, no correlation to the total- or subcategory mean DHI scores was found. A significant correlation was found between vestibular hypofunction and the presence of a heart condition as well as an increased number of comorbidities, respectively.</p>