Background: Nature exposures may be associated with reduced risk for heart disease. The present study examines the relationship between objective measures of neighborhood greenness (vegetative presence) and diagnoses of four forms of heart disease (acute myocardial infarction [AMI], ischemic heart disease, heart failure, and atrial fibrillation), in a large population-based sample of Medicare beneficiaries in Miami-Dade County, Florida. Methods: The sample included 249,405 Medicare beneficiaries ages 65 years and older whose location (ZIP+4) in Miami-Dade County, Florida, did not change from 2010 to 2011. Analyses examined relationships between greenness, measured by mean Normalized Difference Vegetation Index (NDVI) from satellite imagery at the Census block level, and four forms of heart disease in 2011. A series of hierarchical regression analyses, in a multi-level framework, assessed the relationship of greenness to each heart disease diagnosis, adjusting successively for individual sociodemographics and neighborhood median household income. A further final model adjusted for biological risk factors (diabetes, hypertension, and hyperlipidemia). Results: Higher greenness was generally associated with reduced risk of heart disease, in models adjusting for individual sociodemographics and neighborhood income: When compared to the lowest tertile of greenness, the highest tertile of greenness was associated with statistically significant (ps<.01) reduced odds of AMI by 25% (OR=0.75; 95% CI: 0.63, 0.90), ischemic heart disease by 20% (OR=0.80; 95% CI: 0.77, 0.83), heart failure by 16% (OR=0.84; 95% CI: 0.80, 0.88), and a marginally significant reduced odds of atrial fibrillation by 6% (OR=0.94; 95% CI: 0.87, 1.00, p=.067). In addition, the highest tertile of greenness was associated with 19% reduced odds of any of the four forms of heart disease (OR=0.81; 95% CI: 0.78, 0.84) when compared to the lowest tertile of greenness, adjusting for individual sociodemographics and neighborhood income. These associations were attenuated in a final model which added biological risk factors, suggesting that cardiometabolic risk factors may at least partly mediate the observed relationships between greenness and heart disease. Conclusions: Even after adjusting for individual sociodemographics and neighborhood income, neighborhood greenness may be associated with reduced odds of heart disease, possibly as a result of increased time spent outdoors, physical activity, stress mitigation, and/or air pollution. Results suggest that strategies to reduce inequities in area greenness and improve public access to these areas may be a future means of reducing heart disease at the population level.