HIV is the virus that causes AIDS. Illinois has the seventh-highest number of AIDS cases in the nation, with more than 41,000 reported cases since 1981.
The health department encourages people to be tested for HIV because many people infected with the virus don't know they have it.
People knowing their HIV status can help stem the spread of the virus.
Scheduled events include HIV testing and counseling on Sunday at Trinity Church of Christ in Chicago.
On Monday, other testing and counseling events are planned in Champaign, Arcola and Rock Island.
To find free health events near you, call the HIV hotline at 800-243-2437.
(The Associated Press contributed to this report.)