| Election Name: | 2018 Indiana State Senate election |
| Country: | Indiana |
| Type: | legislative |
| Ongoing: | no |
| Previous Election: | 2016 Indiana State Senate election |
| Previous Year: | 2016 |
| Next Election: | 2020 Indiana State Senate election |
| Next Year: | 2020 |
| Seats For Election: | 25 of 50 seats in the Indiana Senate |
| Majority Seats: | 26 |
| Election Date: | November 6, 2018 |
| Image1: | State-of-the-State-2020-041 (49387486086) (cropped).jpg |
| Leader1: | Rodric Bray |
| Party1: | Republican Party (United States) |
| Leaders Seat1: | 37th District |
| Last Election1: | 41 |
| Seats Before1: | 41 |
| Seats1: | 40 |
| Seat Change1: | 1 |
| Popular Vote1: | 673,237 |
| Percentage1: | 64.31% |
| Leader2: | Timothy Lanane |
| Party2: | Democratic Party (United States) |
| Leaders Seat2: | 25th District |
| Last Election2: | 9 |
| Seats Before2: | 9 |
| Seats2: | 10 |
| Seat Change2: | 1 |
| Popular Vote2: | 369,003 |
| Percentage2: | 35.25% |
| Map Size: | 250px |
| President pro tempore | |
| Before Election: | David C. Long |
| Before Party: | Republican |
| After Election: | David C. Long |
| After Party: | Republican |
Elections to the Indiana Senate took place on November 6, 2018. Primary elections were held on May 8, 2018.
| District | Incumbent | Party | Elected Senator | Party | |||
|---|---|---|---|---|---|---|---|
| 1 | Frank Mrvan | Dem | Frank Mrvan | Dem | |||
| 4 | Karen Tallian | Dem | Karen Tallian | Dem | |||
| 6 | Rick Niemeyer | Rep | Rick Niemeyer | Rep | |||
| 11 | Joe Zakas | Rep | Linda Rogers | Rep | |||
| 14 | Dennis Kruse | Rep | Dennis Kruse | Rep | |||
| 15 | Liz Brown | Rep | Liz Brown | Rep | |||
| 17 | Andy Zay | Rep | Andy Zay | Rep | |||
| 19 | Travis Holdman | Rep | Travis Holdman | Rep | |||
| 21 | James R. Buck | Rep | James R. Buck | Rep | |||
| 22 | Ronnie Alting | Rep | Ronnie Alting | Rep | |||
| 23 | Phil Boots | Rep | Phil Boots | Rep | |||
| 25 | Timothy Lanane | Dem | Timothy Lanane | Dem | |||
| 26 | Doug Eckerty | Rep | Mike Gaskill | Rep | |||
| 27 | Jeff Raatz | Rep | Jeff Raatz | Rep | |||
| 29 | Mike Delph | Rep | J. D. Ford | Dem | |||
| 31 | James W. Merritt | Rep | James W. Merritt | Rep | |||
| 38 | Jon Ford | Rep | Jon Ford | Rep | |||
| 39 | Eric Bassler | Rep | Eric Bassler | Rep | |||
| 41 | Greg Walker | Rep | Greg Walker | Rep | |||
| 43 | Chip Perfect | Rep | Chip Perfect | Rep | |||
| 45 | Jim Smith | Rep | Chris Garten | Rep | |||
| 46 | Ron Grooms | Rep | Ron Grooms | Rep | |||
| 47 | Erin Houchin | Rep | Erin Houchin | Rep | |||
| 48 | Mark Messmer | Rep | Mark Messmer | Rep | |||
| 49 | Jim Tomes | Rep | Jim Tomes | Rep | |||
Two districts had a margin of victory under 10%:
Two incumbent senators, both Republicans, chose to not seek reelection.
One incumbent Republican senator ran for reelection but was defeated in the May 8 primary.
| align=center | District 1 • District 4 • District 6 • District 11 • District 14 • District 15 • District 17 • District 19 • District 21 • District 22 • District 23 • District 25 • District 26 • District 27 • District 29 • District 31 • District 38 • District 39 • District 41 • District 43 • District 45 • District 46 • District 47 • District 48 • District 49 |