Leaded fuel used by piston-engine aircraft is the largest source of airborne lead emissions in the United States. Previous studies have found higher blood lead levels in children living near airports where leaded aviation fuel is used. However, little is known about health effects on adults. This study is the first to examine the association between exposure to leaded aviation fuel and adult cardiovascular mortality. We estimate the association between annual piston-engine air traffic and cardiovascular mortality among adults ages 65 and older near 40 North Carolina airports during 2000 to 2017. We use several strategies to minimize the potential for bias due to omitted variables and confounding from other health hazards at airports, including coarsened exact matching, location-specific intercepts, and adjustment for jet-engine and other air traffic that does not use leaded fuel. We find that cardiovascular mortality rates within a few kilometers of single-runway airports were significantly higher in years with more piston-engine air traffic. We do not consistently find a statistically significant association between cardiovascular mortality rates and piston-engine air traffic near multi-runway airports, where there is greater uncertainty in our measure of the distance between populations and aviation exposures. These results suggest that (i) reducing lead emissions from aviation could yield substantial health benefits for adults, and (ii) more refined data are needed to obtain more precise estimates of these benefits.