| Election Name: | Illinois Senate elections, 2008 |
| Country: | Illinois |
| Type: | legislative |
| Ongoing: | no |
| Previous Election: | 2006 Illinois elections#State Senate |
| Previous Year: | 2006 |
| Next Election: | 2010 Illinois Senate election |
| Next Year: | 2010 |
| Seats For Election: | 40 of 59 total seats in the Illinois Senate |
| Majority Seats: | 30 |
| Image1: | John Cullerton (cropped).jpg |
| Leader1: | John Cullerton |
| Party1: | Democratic Party (United States) |
| Leaders Seat1: | 6th-Chicago |
| Last Election1: | 37 |
| Seats1: | 37 |
| Popular Vote1: | 1,749,517 |
| Percentage1: | 54.22% |
| Leader2: | Frank Watson |
| Party2: | Republican Party (United States) |
| Leaders Seat2: | 51st-Greenville |
| Last Election2: | 22 |
| Seats2: | 22 |
| Popular Vote2: | 1,457,074 |
| Percentage2: | 45.15% |
| Map Size: | 350px |
| President | |
| Posttitle: | President-Elect |
| Before Election: | Emil Jones |
| Before Party: | Democratic Party (United States) |
| After Election: | John Cullerton |
| After Party: | Democratic Party (United States) |
The Illinois State Senate Election of 2008 determined, along with 19 senators not up for re-election, the membership of the 96th Illinois State Senate. The Democratic Party retained its majority.
| Illinois State Senate Elections, 2008 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Party | Votes | Percentage | Seats up | Seats not up | Total seats | +/– | ||
| Democratic | 1,791,386 | 54.81% | 24 | 13 | 37 | 0 | ||
| Republican | 1,457,074 | 44.58% | 16 | 6 | 22 | 0 | ||
| Green | 19,818 | 0.61% | 0 | 0 | 0 | 0 | ||
| Independent | 116 | 0.004% | 0 | 0 | 0 | 0 | ||
| Totals | 3,268,394 | 100.00% | 40 | 19 | 59 | — | ||
The following are results by individual districts.