A 26-year-old woman developed congestive heart failure (CHF) secondary to idiopathic dilated cardiomyopathy. Despite aggressive pharmacological therapy, her disease progressed over the next year, causing massive edema and dyspnea at rest. Although a sleep study showed no clinically significant sleep apnea, she was treated with nocturnal continuous positive airway pressure (CPAP). Following application of CPAP, a remarkable improvement in her condition was observed, with resolution of her edema and alleviation of dyspnea. Left ventricular ejection fraction increased from 29% to 43% and left ventricular dimensions decreased. Previous studies have demonstrated that nocturnal CPAP exerts a number of favourable effects on cardiovascular function in patients with CHF who suffer from a coexisting sleep apnea disorder. This report illustrates that CPAP can also have beneficial long term effects on the failing heart even in the absence of clinically significant sleep apnea.