Purpose: Our study aimed to evaluate the effects of chronic hypoxic state in Obstructive Sleep Apnea Syndrome (OSAS) on brainstem pathways using Vestibular Evoked Myogenic Potential (VEMP) test and to investigate the presence of new markers likely to be correlated with the severity of the disease. Methods: The study was planned as prospective and double blind. A total of 60 patients (120 ears) diagnosed with mild, moderate and severe OSAS were included in the study and the patients are grouped as 20 patients in each group. Twenty volunteer healthy individuals (40 ears) shown to be without OSAS were included in the study. VEMP measurements were made in 60 study group patients (120 ears) and in 20 healthy controls (40 ears). The groups were compared in terms of variables such as the acquisition rate of oVEMP and cVEMP waves, interval between the waves, latency and amplitude of the waves. p < 0.05 values were considered as significant. Results: The results of cVEMP test showed that the rate of wave acquisition in the moderate and severe OSAS groups was significantly lower than the control group and mild OSAS groups (p = 0.008). There was no difference between the control group and the mild OSAS group in terms of the rate of obtaining the wave (p > 0.05). In the moderate and severe OSAS groups, P1N1 amplitude and N1P2 amplitude values were found to be significantly lower than the mild OSAS group (p = 0.007 and p = 0.017, respectively). In the oVEMP test, there was no significant difference between the mild OSAS group and the control group in terms of the wave yield (p > 0.05); however, it was found that the rate of wave acquisition in the moderate and severe OSAS groups was significantly lower than the mild OSAS group (p = 0.041). There was inverse correlation between the N1P2 interval and P1N1 amplitude value and AHI in simple regression analysis and multiple regression analysis (p = 0.012 and p = 0.021; p = 0.009 and p = 0.040, respectively). Conclusion: The negative effects of chronic intermittent hypoxia related with OSAS on the brainstem and vestibular system can be demonstrated by VEMP tests. Especially, the inability to obtain the wave is the most important finding showing this situation. Also, we think that N1P2 interval and P1N1 amplitude markers can be used to detect the subclinical negative effect of chronic hypoxia on vestibular nuclei in the brainstem.