OBJECTIVES: To determine the prevalence and correlates of nocturia in community-dwelling older adults. DESIGN: Planned secondary analysis of cross-sectional data from the University of Alabama at Birmingham Study of Aging population-based survey. SETTING: Participants' homes. PARTICIPANTS: One thousand older adults (aged 65-106) recruited from Medicare beneficiary lists between 1999 and 2001. The sample was selected to include 25% each African-American women, African-American men, white women, and white men. MEASUREMENTS: In-person interviews included sociodemographic information, medical history, Mini-Mental State Examination (MMSE) score, and measurement of body mass index (BMI). Nocturia was defined in the main analyses as rising two or more times per night to void. RESULTS: Nocturia was more common in men than women (63.2% vs 53.8%, odds ratio (OR)=1.48, 95% confidence interval (CI)=1.15-1.91, P=.003) and more common in African Americans than whites (66.3% vs 50.9%, OR=1.89, 95% CI=1.46-2.45, P<.001). In multiple backward elimination regression analysis in men, nocturia was significantly associated with African-American race (OR=1.54) and BMI (OR=1.22 per 5 kg/m(2)). Higher MMSE score was protective (OR=0.96). In women, nocturia was associated with older age (OR=1.21 per 5 years), African-American race (OR=1.64), history of any urine leakage (OR=2.17), swelling in feet and legs (OR=1.67), and hypertension (OR=1.62). Higher education was protective (OR=0.92). CONCLUSION: Nocturia in community-dwelling older adults is a common symptom associated with male sex, African-American race, and some medical conditions. Given the significant morbidity associated with nocturia, any evaluation of lower urinary tract symptoms should include assessment for the presence of nocturia.