The United States suffered 33,686 deaths in battle in the Korean War. There were an additional 2,830 deaths which occurred during the war, but were not related to any battle.
In addition to the more than 30,000 deaths in combat, the United States had 92,134 soldiers become wounded or otherwise incapacitated during the war. Many of these casualties suffered by the United States military occurred during battles with the Chinese army, which contributed the largest opposing force to the Korean War. As well, 4,759 United States troops were reported missing in battle with their status ultimately unknown.
These losses represented the largest expenditure of American life since the Second World War, and would remain so until the Vietnam War, two years later. It is currently estimated that the casualties suffered in the Korean War would make it the fifth most costly war (in terms of lives lost) in American history. All in all, roughly 0.020 percent of the American population was killed fighting in Korea.
This war was the last time the United States faced a similarly-equipped opponent in large-scale open warfare. After the Korean War and the Vietnam War, the United States never suffered casualties on such an enormous scale again.