Diagnosed obstructive sleep apnea affects 2-4% of middle aged Americans and represents a substantial health care burden. Despite its prevalence, little is known about the demographic characteristics or clinical management of sleep apnea patients hospitalized for other comorbidities and surgeries. The aim of this study was to provide a broad characterization of the epidemiology of sleep apnea in hospitalized patients in the United States and to describe the trends in the management of their sleep apnea during their hospitalizations. Using the 2004 National Hospital Discharge Survey (NHDS), a nationally representative sample of discharges from nonfederal acute care hospitals in the United States, cases of sleep apnea were obtained from hospital discharge records coded according to the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). The specific objectives of this study were to: (1) describe the prevalence of hospitalized unspecified sleep apnea individuals according to age, gender, and comorbidities; (2) estimate prevalence of the use of continuous positive airway pressure (CPAP) therapy during hospitalization and describe those uses according to hospital ownership and size. A retrospective analysis of data of hospitalized patients with unspecified sleep apnea from the 2004 National Hospital Discharge Survey (NHDS) was completed. In 2004, the NHDS collected data for approximately 371,000 discharges from a sample of 439 nonfederal short-stay hospitals. An estimated 34.9 million inpatients were discharged from nonfederal short-stay hospitals in 2004. Patients diagnosed with unspecified sleep apnea were identified using the International Classification of Diseases (Ninth Revision), Clinical Modification (ICD-9-CM) code of 780.57, which, before 2005, was the sole diagnostic code under which obstructive sleep apnea was listed. A subset of these patients, those receiving CPAP therapy, was further identified using the ICD-9-CM procedural code 93.90. Review of weighted discharge data identified a total of 293,478 estimated cases of unspecified sleep apnea. Approximately 64% of these individuals were between the ages 40 and 69 years old with a gender distribution of 55.3% males. The most common diagnoses in hospitalized sleep apnea patients were morbid obesity, congestive heart failure, coronary artery disease, exacerbation of COPD, and pneumonia. Sleep apnea was managed through the standardized therapy, CPAP, in 5.8% of hospitalized patients and CPAP therapy was more likely to be utilized in sleep apnea patients hospitalized in a government hospital than in a for-profit hospital. In conclusion, only a small percentage (5.8%) of patients diagnosed with unspecified sleep apnea in the 2004 NHDS were provided with CPAP therapy during hospitalization. There appear to be institutional differences in the utilization of CPAP therapy in hospitals across the United States. These findings suggest that in the United States, the management of sleep apnea in hospitalized patients is deficient, and the use of CPAP therapy in the hospital warrants further investigation.