Background/Aims Prior studies have shown higher green cover levels to be associated with numerous beneficial health outcomes. We sought to determine if residential green cover was associated with direct health care costs. Methods We studied 5,189,303 members of Kaiser Permanente Northern California (KPNC), linking Normalized Differentiated Vegetation Index (NDVI) satellite data to direct health care costs for 2013-2017. Using generalized linear regression to adjust for demographic, socioeconomic and environmental factors, we examined the association between direct health care costs and green cover within 250, 500, and 1000 meters (m) of an individual’s residence. Direct health care costs were determined from the KPNC Cost Management Information System, which captures administrative and patient care costs for each clinical encounter. Results We observed a significant trend between higher levels of residential green cover and lower direct health care costs, with the bulk of this association occurring in the top five deciles of green cover. The relative rate of total cost for the highest compared to the lowest decile of NDVI was 0.86 (95% CI 0.85-0.87). The association was robust to adjustment from a broad array of confounders and was largely driven by costs associated with hospitalization, outpatient visits, and emergency department visits. Individuals in the top decile of residential green cover had adjusted health care costs of approximately $300 per person per year less than individuals residing in the bottom or least green decile. Sensitivity analyses related to buffer size and an alternative measure of green space (tree canopy cover, yielded consistent findings. Analyses that included adjustment for comorbidity were consistent with the hypothesis that green cover reduces health care costs by improving health status. Conclusion Above-median green cover was associated with lower direct health care costs, raising the possibility that residential greening can have a significant healthcare cost impact across the population.