Activation of oxytocin receptors has shown benefits in animal models of Obstructive Sleep Apnea (OSA). We tested if nocturnal oxytocin administration could have beneficial effects in OSA patients. 8 patients diagnosed with OSA were administered intranasal oxytocin (40 i.u.). Changes in cardiorespiratory events during sleep, including apnea and hypopnea durations and frequency, risk of event-associated arousals, and heart rate variability were assessed. Oxytocin significantly increased indices of parasympathetic activity, including heart rate variability, total sleep time, and the Post-Polysommogram Sleep Assessment (PPSA) score, an index of self-reported sleep satisfaction. Although the Apnea-Hypopnea Index (AHI) was not significantly changed with oxytocin administration, when apnea and hypopnea events were compared independently, the frequency of hypopneas, but not apneas, were significantly (p<.005) decreased with oxytocin treatment. Both apneas and hypopneas were significantly shortened in duration with oxytocin treatment. Oxytocin treatment significantly decreased the percent of apnea and hypopnea events that were accompanied with an arousal. Oxytocin administration has the potential to restore cardiorespiratory homeostasis and reduce some clinically important (objective and patient-reported) adverse events that occur with OSA. Additional studies are needed to further understand the mechanisms by which oxytocin promotes these changes in cardiorespiratory and autonomic function in OSA patients.