Illinois currently has 3,000 National Guardsmen in Afghanistan, part of the state's largest deployment since World War II.
Guard spokesman Maj. Brad Leighton says the two soldiers belonged to the guard's 33rd Infantry Brigade Combat Team and were among more than 2,900 guardsmen from the brigade deployed in Afghanistan.
The two guardsmen were among four coalition soldiers killed in southern Afghanistan when their vehicle struck a roadside bomb.
The Associated Press contributed to this report.