There is increasing evidence that sleep-disordered breathing may contribute to the progression and prognosis of chronic heart failure (CHF). The presence of sleep-disordered breathing, especially central sleep apnea syndrome (CSAS), commonly referred to as Cheyne-Stokes respiration, may be a potent predictor of adverse prognosis in patients with CHF. CSAS is estimated to be present in 25% to 50% of patients with CHF and is related to the severity of CHF, exercise tolerance (VE/VCO₂ slope), and neurohormoral derangements. We performed a multicenter randomized, controlled trial to clarify the effects of nocturnal home oxygen therapy (HOT) in patients with CSAS due to CHF (New York Heart Association class II or III, left ventricular ejection fraction <45%, and oxygen desaturation index >5 dips/hour). The CHF-HOT study demonstrated significant improvements in the apnea-hypopnea index, left ventricular ejection fraction, and the specific activity scale following 12 weeks of nocturnal HOT. The subanalysis revealed significant reductions in the frequencies of hospitalization (2.1 to 0.5 times/year), emergency visits (2.5 to 0.7 times/year) as compared with those before the introduction of nocturnal HOT. The pathophysiology of CSAS is being clarified, and novel treatments should be developed.