| Election Name: | 2008 Wisconsin State Senate election |
| Country: | Wisconsin |
| Type: | legislative |
| Ongoing: | no |
| Previous Election: | 2006 Wisconsin State Senate election |
| Previous Year: | 2006 |
| Next Election: | 2010 Wisconsin Senate election |
| Next Year: | 2010 |
| Seats For Election: | 16 of 33 seats in the Wisconsin Senate |
| Majority Seats: | 17 |
| Election Date: | November 4, 2008 |
| Image1: | Russ Decker 2008 CROPPED.jpg |
| Image1 Size: | x150px |
| Leader1: | Russ Decker |
| Party1: | Democratic Party of Wisconsin |
| Last Election1: | |
| Seats Before1: | 18 |
| Seats1: | 8 |
| Seats After1: | 18 |
| Swing1: | 3.1 |
| Popular Vote1: | 666,668 |
| Percentage1: | 52.74% |
| Image2 Size: | x150px |
| Leader2: | Scott L. Fitzgerald |
| Party2: | Republican Party of Wisconsin |
| Seats Before2: | 15 |
| Seats2: | 8 |
| Seats After2: | 15 |
| Swing2: | 3.7 |
| Popular Vote2: | 575,543 |
| Percentage2: | 45.53% |
| President | |
| Before Party: | Democratic Party of Wisconsin |
| Before Election: | Fred Risser |
| After Party: | Democratic Party of Wisconsin |
| After Election: | Fred Risser |
The 2008 Wisconsin Senate election was held on Tuesday, November 4, 2008. Sixteen of the 33 seats in the Wisconsin Senate were up for election - the even-numbered districts. Prior to the election 17 seats were held by Democrats, 14 were held by Republicans, and 2 seats were vacant.
The primary was held on September 9, 2008, and the filing deadline was July 8, 2008.
| Seats | Party (majority caucus shading) | Total | |||
|---|---|---|---|---|---|
| Democratic | Republican | ||||
| Last election (2006) | 9 | 8 | 17 | ||
| Total after last election (2006) | 18 | 15 | 33 | ||
| Total before this election | 18 | 15 | 33 | ||
| Up for election | 8 | 8 | 16 | ||
| of which: | Incumbent retiring | 1 | 1 | 2 | |
| Vacated | 1 | 1 | 2 | ||
| Unopposed | 4 | 2 | 6 | ||
| This election | 8 | 8 | 16 | ||
| Change from last election | |||||
| Total after this election | 18 | 15 | 33 | ||
| Change in total | |||||
Seats where the margin of victory was under 10%:
| Dist. | Incumbent | This race[2] | ||||||
|---|---|---|---|---|---|---|---|---|
| Member | Party | Firstelected | Status | Candidates | Results | |||
| 02 | Rep. | 1987 | Incumbent Ran |
| Incumbent re-elected | |||
| 04 | Dem. | 2004 | Incumbent Ran |
| Incumbent re-elected | |||
| 06 | Dem. | 2003 | Incumbent Ran |
| Incumbent re-elected | |||
| 08 | Rep. | 1992 | Incumbent Ran |
| Incumbent re-elected | |||
| 10 | Rep. | 2000 | Incumbent Ran |
| Incumbent re-elected | |||
| 12 | colspan="4" | --Vacant-- |
| New member elected. Democratic hold | ||||
| 14 | Rep. | 2004 | Incumbent Ran |
| Incumbent re-elected | |||
| 16 | Dem. | 2004 | Incumbent Ran |
| Incumbent re-elected | |||
| 18 | colspan="4" | --Vacant-- |
| New member elected. Republican hold | ||||
| 20 | Rep. | 2004 | Incumbent Ran |
| Incumbent re-elected | |||
| 22 | Dem. | 1996 | Incumbent Ran |
| Incumbent re-elected | |||
| 24 | Dem. | 2003 | Incumbent Ran |
| Incumbent re-elected | |||
| 26 | Dem. | 1962 | Incumbent Ran |
| Incumbent re-elected | |||
| 28 | Rep. | 1998 | Incumbent Ran |
| Incumbent re-elected | |||
| 30 | Dem. | 2000 | Incumbent Ran |
| Incumbent re-elected | |||
| 32 | Rep. | 2004 | Incumbent Ran |
| Incumbent re-elected | |||