The aim of this study was to identify the prevalence of heightened risk for obstructive sleep apnea (OSA) and its clinical predictors in a heterogeneous diagnostic group of hospitalized psychiatric patients. Ninety-one consecutive psychiatric inpatients were administered the STOP-BANG and Epworth Sleepiness Scale (ESS) inventories. Medical and demographic information was gathered from inpatient clinical charts. Predictors of high OSA risk score were analyzed by a multivariate regression model. A total of 58.2% (53 patients) were determined to have a high risk for OSA. The predictors of high OSA risk were use of mood stabilizers, use of CNS depressants, use of CNS stimulants, and excessive daytime sleepiness measured by ESS. The risk of OSA was high in psychiatric inpatients, and particularly elevated in older patients and those taking commonly utilized psychiatric medications.