Obstructive sleep apnea presenting with nocturnal angina, heart failure, and near-miss sudden death. An obese woman with a one-year history of episodic nocturnal chest pain was admitted because of shock and pulmonary edema. A clinical diagnosis of acute myocardial infarction and cardiogenic shock was made. She was ventilated and successfully resuscitated. Subsequent investigations showed no evidence of cardiac dysfunction or coronary disease, but sleep study confirmed the diagnosis of obstructive sleep apnea syndrome (OSAS). We suggest that the nocturnal angina and heart failure in this patient might have resulted from extreme hypoxemia produced by OSAS. This case raised the possibility that the high cardiovascular mortality rate reported in OSAS might not necessarily relate to underlying coronary artery disease. Further investigations are required to delineate the true incidence of coronary disease in patients with OSAS. 