Purpose: To examine sleep duration and its demographic and clinical correlates in patients attending outpatient clinics attached to general hospitals. Design and Methods: A total of 4,399 outpatients participated in the study. Sleep duration (short sleep, <7 h/day; long sleep, >8 h/day; and medium sleep, 7–8 h/day) was assessed. Findings: The proportions of short and long sleep duration were 39.5% and 10.3%, respectively. Significant associations between short sleep and any type of sleep disturbances, age, education level, depressive symptoms, and rural residence were found. Long sleep was associated with age, education level, being unemployed, and depressive and anxiety symptoms. Practice Implications: Short sleep duration is common among Chinese general hospital outpatients. Due to its negative effects, screening and interventions for short sleep are needed in this population.