The victim was a suburban Cook County resident with "other significant medical conditions that increased vulnerability to the H1N1 virus," the Department of Health said in a release.
Anyone who had close contact to the victim has received appropriate medical attention, the release said.
The Health Department declined to identify the person who died.
On Monday, the Health Department said a Chicagoan died from H1N1 flu. That victim was a 22-year-old man who also had health issues other than contracting the flu.
Illinois currently has 975 confirmed cases of swine flu, with 717 of those in Chicago and Cook County.