Background <p>This study aims to investigate the common arrhythmias seen in patients with obstructive sleep apnea (OSA) and the association between the rhythm Holter values and OSA.</p> Methods <p>A 24-hour rhythm Holter monitor was attached to 90 patients diagnosed with obstructive sleep apnea (mean age 48.65 ± 8.41). All patients’ medical histories were taken, and laboratory tests were conducted. Single-night polysomnographies were scored under the recommendations of the American Academy of Sleep Medicine.</p> Results <p>There was no significant difference in age between the study and the control groups. No statistically significant difference was observed between the groups regarding gender distribution. The study group’s minimum heart rate was significantly lower. The difference in supraventricular ectopy percentage (SVE) between the study and control groups was statistically significant. An important difference was also observed between the groups in terms of ventricular ectopics (VE) percentage.</p> Conclusions <p>In OSA, hypoxemia may increase vagal tone and create a predisposition for arrhythmias. Also, increased vagal activity observed in OSA, leads to relative bradycardia during obstructive events which may be due to the diving reflex, and supraventricular and ventricular arrhythmias. The rhythm Holter is a useful non-invasive test for the early arrhythmia diagnosis in patients with OSA. Also, conducting polysomnography in patients with arrhythmias detected by Holter monitoring may facilitate early OSA diagnosis and improve treatment.</p>