Objectives: The objective of this study is to investigate the distribution and determinants of diastolic function in a middle-aged cohort of African Americans (AA). Background: The distribution and determinants of left ventricular (LV) diastolic function in AA are not well-described despite high rates of AA with diastolic heart failure and a five-fold higher risk of death in those with diastolic dysfunction (DD) compared to normal diastolic function. Methods: Four categories of diastolic function were defined in JHS participants undergoing echocardiograms at the first examination (2001-2004) using mitral and pulmonary vein velocities. Investigators used logistic regression to assess the independent relation of DD to traditional risk factors and LV systolic dysfunction. Results: Of the 3,571 study participants (mean age, 56 ± 12 years; 63.9% female), 70.4% had normal diastolic function, and 18.0%, 10.6%, and 0.9% had mild, moderate, and severe DD, respectively. In the multivariable analysis, DD was significantly related to age (OR 1.2, 95% CI 1.1-1.4), male sex (OR 1.3 CI 1.0-1.5), LV systolic dysfunction (OR 1.5, CI 1.2-2.0), body mass index (OR 0.8, CI 0.8-0.9), and heart rate (OR 1.2; CI 1.1-1.2). The severity of DD was significantly related with age (OR 0.3; CI 0.3, 0.4), male sex (OR 1.6; CI 1.2-2.2), hypertension (OR 0.6, CI 0.4-0.8), and heart rate (OR 0.7; CI 0.6-0.8). Conclusion: This is the largest community-based analysis of LV diastolic function in middle-aged AA. DD was present in 29.5% and independently related to several traditional risk factors and LV systolic dysfunction. © 2009 Mosby, Inc. All rights reserved.