John Stone, 38, of Montville, Conn., was watching the first inning of the Yankees' 5-3 loss to the Los Angeles Angels on Wednesday when he saw a woman become distressed about 10 rows in front of him.
"I saw a bit of commotion and I ran down there," he said.
The woman was "panicking and on the verge of passing out," a police source said. Stone had trouble at first getting in position to perform the Heimlich maneuver.
"She was slumped over and that's not the best position," he said. "I was able to maneuver her and give her five or six compressions. Eventually, what was down there came up."
The woman was "extremely thankful," said Stone, no stranger to heroic acts.
As a staff sergeant and medic with the Connecticut Army National Guard, he served in the Iraqi war zone from 2004 to 2005.
Stone said saving a choking victim at a ballpark is "not even close" to his experience tending to wounded soldiers and admitted, "It took me a minute to get my mind around doing it at Yankee Stadium."
The Yankees showed their appreciation by upgrading Stone's seat to the front row.