| Election Name: | 1999 National Assembly for Wales election |
| Country: | Wales |
| Type: | parliamentary |
| Ongoing: | no |
| Election Date: | 6 May 1999 |
| Next Election: | 2003 National Assembly for Wales election |
| Next Year: | 2003 |
| Seats For Election: | All 60 seats to the National Assembly for Wales |
| Majority Seats: | 31 |
| Turnout: | 46.3% |
| Leader1: | Alun Michael |
| Party1: | Welsh Labour |
| Leaders Seat1: | Mid & West Wales |
| Seats1: | 28 |
| 1Blank: | FPTP Vote |
| 1Data1: | 384,671 |
| First Secretary | |
| Posttitle: | First Secretary after election |
| After Election: | Alun Michael |
| After Party: | Welsh Labour |
| 2Blank: | Percentage |
| 3Blank: | List Vote |
| 4Blank: | Percentage |
| 2Data1: | 37.6% |
| 3Data1: | 361,657 |
| 4Data1: | 35.4% |
| Leader2: | Dafydd Wigley |
| Party2: | Plaid Cymru |
| Leaders Seat2: | Caernarfon |
| Seats2: | 17 |
| 1Data2: | 290,572 |
| 2Data2: | 28.4% |
| 3Data2: | 312,048 |
| 4Data2: | 30.5% |
| Leader4: | Rod Richards |
| Party4: | Welsh Conservatives |
| Leaders Seat4: | North Wales |
| Seats4: | 9 |
| 1Data4: | 162,133 |
| 2Data4: | 15.8% |
| 3Data4: | 168,206 |
| 4Data4: | 16.5% |
| Leader5: | Michael German |
| Party5: | Welsh Liberal Democrats |
| Leaders Seat5: | South Wales East |
| Seats5: | 6 |
| 1Data5: | 137,857 |
| 2Data5: | 13.5% |
| 3Data5: | 128,008 |
| 4Data5: | 12.5% |
The 1999 National Assembly for Wales election was held on Thursday 6 May 1999 to elect 60 members to the Senedd, at the time called the National Assembly for Wales (Welsh Parliament;). It was the first devolved general election held in Wales after the successful 1997 Welsh devolution referendum. The election was held alongside the Scottish Parliament election (also the first of its kind) and English local elections.
Although Welsh Labour were the biggest party, they did not gain enough seats to form a majority government and instead entered into coalition with the Liberal Democrats. The election was marked by the historically high level of support for Plaid Cymru, who won their highest share of the vote in any Wales-wide election and remains their highest number of seats in a Senedd election to date. The party won considerable support in traditionally safe Labour areas such as the South Wales Valleys, winning Rhondda and Islwyn and narrowly failing to win a number of other seats.
The overall turnout of voters was 46.3%.[1] This would remain the highest ever turnout for a devolved election in Wales until the 2021 Senedd election, which saw 46.6 of voters cast their ballot.[2]
|-| style="background-color:white" colspan=15 | |-!rowspan=3 colspan=2 | Parties!colspan=10 | Additional member system!rowspan=2 colspan=5 | Total seats|-!colspan=5 |Constituency!colspan=5 |Region|-! Votes !! % !! +/− !! Seats !! +/− ! Votes !! % !! +/− !! Seats !! +/−! Total !! +/− !! %|-|-| || Total || 1,023,225 || || || 40 || || 1,019,987 || || || 20 || || 60 || |||}
|-! colspan=2 style="width: 200px"|Constituency! style="width: 150px"|Elected member! style="width: 300px"|Result |-! colspan="2" style="width: 150px"|Party! Elected candidates! style="width: 40px"|Seats! style="width: 40px"|+/−! style="width: 50px"|Votes! style="width: 40px"|%! style="width: 40px"|+/−%|-
|-! colspan=2 style="width: 200px"|Constituency! style="width: 150px"|Elected member! style="width: 300px"|Result |-! colspan="2" style="width: 150px"|Party! Elected candidates! style="width: 40px"|Seats! style="width: 40px"|+/−! style="width: 50px"|Votes! style="width: 40px"|%! style="width: 40px"|+/−%|-
|-! colspan=2 style="width: 200px"|Constituency! style="width: 150px"|Elected member! style="width: 300px"|Result |-! colspan="2" style="width: 150px"|Party! Elected candidates! style="width: 40px"|Seats! style="width: 40px"|+/−! style="width: 50px"|Votes! style="width: 40px"|%! style="width: 40px"|+/−%|-
|-! colspan=2 style="width: 200px"|Constituency! style="width: 150px"|Elected member! style="width: 300px"|Result |-! colspan="2" style="width: 150px"|Party! Elected candidates! style="width: 40px"|Seats! style="width: 40px"|+/−! style="width: 50px"|Votes! style="width: 40px"|%! style="width: 40px"|+/−%|-
|-! colspan=2 style="width: 200px"|Constituency! style="width: 150px"|Elected member! style="width: 300px"|Result |-! colspan="2" style="width: 150px"|Party! Elected candidates! style="width: 40px"|Seats! style="width: 40px"|+/−! style="width: 50px"|Votes! style="width: 40px"|%! style="width: 40px"|+/−%|-
See main article: Opinion polling for the 1999 National Assembly for Wales election.