| 142nd Regiment, Illinois Volunteer Infantry | |
|---|---|
 Illinois state flag | |
| Active | June 18, 1864, to October 27, 1864 |
| Country | United States |
| Allegiance | Union |
| Branch | Infantry |
The 142nd Regiment, Illinois Volunteer Infantry was an infantry regiment that served in the Union Army during the American Civil War. It was among the scores of regiments that were raised in the summer of 1864 as Hundred Days Men, part of an effort to augment existing manpower for an all-out push to end the war within 100 days.