Wounded in action (WIA) describes combatants who have been wounded while fighting in a combat zone during wartime, but have not been killed. Typically, it implies that they are temporarily or permanently incapable of bearing arms or continuing to fight. Generally, the Wounded in Action are far more numerous than those killed. Common combat injuries include second and third degree burns, broken bones, shrapnel wounds, brain injuries, spinal cord injuries, nerve damage, paralysis, loss of sight and hearing, post-traumatic stress disorder (PTSD), and limb loss.

For the U.S. military, becoming WIA in combat generally results in subsequent conferral of the Purple Heart, because the purpose of the medal itself (one of the highest awards, military or civilian, officially given by the American government) is to recognize those killed, incapacitated, or wounded in battle.