In every election cycle a certain number of representatives retire or run for other offices leaving behind open seats for their parties to defend. Here are the number of retirements in recent years:
| Year | Democrats | Republicans |
| 2018 | 18 | 34 |
| 2016 | 8 | 20 |
| 2014 | 16 | 25 |
| 2012 | 23 | 20 |
| 2010 | 17 | 20 |
| 2008 | 6 | 27 |
| 2006 | 9 | 18 |
This cycle, 12 Democrats, 36 Republicans and 1 Libertarian are retiring at the end of their current term.
Here are the announced retirements, sorted on PVI (Cook Partisan Voting Index).
Any seat between R+5 and D+5 is a swing district that has to be fought over, even more so
if occupied by the "wrong" party.
| Representative | Party | District | PVI | Reason for retirement |
| Mac Thornberry | Republican | TX-13 | R+33 | If he can't be a high-ranking committee member anymore, he's not interested. |
| Mike Conaway | Republican | TX-11 | R+32 | If he can't be a high-ranking committee member anymore, he's not interested, either. |
| Doug Collins | Republican | GA-09 | R+31 | Running for Kelly Loeffler's Senate seat |
| David Roe | Republican | TN-01 | R+28 | He is a doctor and has long been unhappy in the House |
| John Ratcliffe | Republican | TX-04 | R+28 | He resigned to become Donald Trump's Director of National Intelligence |
| Tom Graves | Republican | GA-14 | R+27 | Illness: He's sick of Donald Trump |
| Roger Marshall | Republican | KS-01 | R+24 | He is running for Pat Roberts' Senate seat |
| Rob Bishop | Republican | UT-01 | R+26 | If he can't be a high-ranking committee member anymore, he's also not interested. |
| John Shimkus | Republican | IL-15 | R+21 | He doesn't like being in the minority |
| Martha Roby | Republican | AL-02 | R+16 | Alabama may lose a district in 2020 |
| Bradley Byrne | Republican | AL-01 | R+15 | He is running to unseat Sen. Doug Jones (D-AL) |
| Ralph Abraham | Republican | LA-05 | R+15 | He promised to serve only three terms and did that |
| Mark Meadows | Republican | NC-11 | R+13 | Became Trump's chief of staff |
| Francis Rooney | Republican | FL-19 | R+13 | He doesn't want to be on board the S.S. Trump anymore |
| Paul Mitchell | Republican | MI-10 | R+13 | He hates the bitter partisanship in D.C. |
| Jim Sensenbrenner | Republican | WI-05 | R+13 | He's 76 and has been in Congress over 40 years. What's the point of staying? |
| Bill Flores | Republican | TX-17 | R+12 | God and his wife told him to spend more time with his family |
| Duncan Hunter | Republican | CA-50 | R+11 | Hunter had to resign because he's moving from the House to the big house |
| Greg Gianforte | Republican | MT-AL | R+11 | Gianforte is running for governor of Montana |
| Greg Walden | Republican | OR-02 | R+11 | He doesn't relish another two (or more) years in the minority; too moderate for the modern GOP |
| Steve King | Republican | IA-04 | R+11 | Primaried |
| Steve Watkins | Republican | KS-02 | R+10 | Primaried |
| Pete Olson | Republican | TX-22 | R+10 | Olson was facing a rematch of a race he nearly lost in 2018 |
| Ted Yoho | Republican | FL-03 | R+9 | Said he would serve only four terms, and is going to stick with that |
| Susan Brooks | Republican | IN-05 | R+9 | She is a moderate in a far-right party |
| Paul Cook | Republican | CA-08 | R+9 | He is running for San Bernadino Board of Supervisors [sic] |
| Kenny Marchant | Republican | TX-24 | R+9 | He would probably lose |
| Rob Woodall | Republican | GA-07 | R+9 | He would probably lose |
| Denver Riggleman | Republican | VA-05 | R+6 | Primaried |
| Ross Spano | Republican | FL-15 | R+6 | Primaried |
| Scott Tipton | Republican | CO-03 | R+6 | Primaried |
| Justin Amash | Libertarian | MI-03 | R+6 | Amash left the Republican Party in protest of Donald Trump, then announced his retirement |
| Peter King | Republican | NY-02 | R+3 | At 75, says he's weary of the job |
| Will Hurd | Republican | TX-23 | R+1 | He would also probably lose, and is also a moderate in a far-right party |
| Dave Loebsack | Democratic | IA-02 | D+1 | He originally planned to serve only 12 years, but stayed 2 more |
| George Holding | Republican | NC-02 | D+4 | Redistricting took his R+7 district to D+4, and Holding decided reelection was not possible |
| Denny Heck | Democratic | WA-10 | D+5 | He misses his wife and is weary of being in Congress |
| Dan Lipinski | Democratic | IL-03 | D+6 | Primaried |
| Nita Lowey | Democratic | NY-17 | D+7 | She's 82 and has been in Congress 31 years |
| Pete Visclosky | Democratic | IN-01 | D+7 | Democrats are moving too far left for his taste |
| Ben Ray Luján | Democratic | NM-03 | D+8 | Running to replace retiring Sen. Tom Udall (D-NM) |
| Joe Kennedy | Democratic | MA-04 | D+9 | Kennedy is challenging Sen. Ed Markey in the Democratic primary |
| Mark Walker | Republican | NC-06 | D+11 | Redistricting took his R+9 district to D+11, and Walker decided reelection was really not possible |
| Susan Davis | Democratic | CA-53 | D+14 | She says she wants to live at home in San Diego |
| Tulsi Gabbard | Democratic | HI-02 | D+19 | Says she wanted to focus on her unsuccessful presidential bid |
| Eliot Engel | Democratic | NY-16 | D+24 | Primaried |
| William Lacy Clay | Democratic | MO-01 | D+29 | Primaried |
| Jose Serrano | Democratic | NY-15 | D+44 | Serrano has Parkinson's disease |