| Country: | Northern Territory |
| Type: | parliamentary |
| Ongoing: | no |
| Election Date: | 31 July 1999 |
| Party1: | Country Liberal Party |
| Popular Vote1: | 1,599 |
| Percentage1: | 46.4% |
| Swing1: | 27.4 |
| Candidate2: | Nicole Cridland |
| Party2: | Australian Labor Party (Northern Territory Branch) |
| Popular Vote2: | 1,396 |
| Percentage2: | 40.5% |
| Swing2: | 14.3 |
| Candidate3: | Peter Gandofi |
| Party3: | Independent politician |
| Popular Vote3: | 352 |
| Percentage3: | 10.2% |
| Swing3: | 10.2 |
| 2Blank: | TPP swing |
| 1Data1: | 53.3% |
| 2Data1: | 20.5 |
| 1Data2: | 46.7% |
| 2Data2: | 20.5 |
| MP | |
| Before Party: | Country Liberal Party |
| After Party: | Country Liberal Party |
A by-election for the seat of Blain in the Northern Territory Legislative Assembly was held on 31 July 1999. The by-election was triggered by the resignation of Country Liberal Party (CLP) member Barry Coulter, a former Deputy Chief Minister. Coulter had held Blain, and its predecessors Berrimah and Palmerston, since 1983.
The CLP selected Terry Mills, a private school Principal, as its candidate. The Labor candidate was Nicole Cridland.