BACKGROUND: Obstructive sleep apnea (OSA) has been associated with multiple cardiovascular comorbidities. Despite increased awareness of OSA and its treatments, the management of OSA in the hospital setting remains below expectations. METHODS: We retrospectively reviewed the demographics, clinical characteristics, and hospital course on 413 consecutive patients with a history of OSA on domiciliary CPAP therapy admitted to the general medical ward and analyzed the prevalence of CPAP use and its effect on length of stay (LOS), 30-day readmission rate, and time-to-readmission in our tertiary care teaching hospital. RESULTS: Of the 413 study participants, 264 (64.0 %) patients were receiving CPAP during their hospital admission. Patients who were receiving CPAP therapy during their hospitalization had a significantly higher body mass index (BMI) (41.4 vs. 36.8 kg/m(2), p < 0.001) and were more likely to be African-American (p = 0.01) and have congestive heart failure (CHF) (42.0 vs. 31.0 %, p = 0.038) peripheral vascular disease (PVD) (26.0 vs. 15.0 %, p = 0.013), and uncomplicated diabetes mellitus (p = 0.001) than those who were not. CPAP therapy in the hospital setting did not affect LOS (4.7 vs. 4.0 days, p = 0.291), readmission rate (11.0 % for both groups), or time-to-readmission (20.8 vs. 22.3 days, p = 0.762). CONCLUSION: The majority of patients who are on domiciliary CPAP therapy were receiving CPAP therapy while admitted to the general medical ward of a tertiary care academic hospital. Presence of comorbid conditions such as obesity and certain cardiovascular diseases may have increased the likelihood of prescribing CPAP therapy while in the hospital. In-hospital CPAP therapy did not appear to significantly influence short-term outcomes such as hospital LOS, readmission rate, or time-to-readmission.