Portuguese legislative election, 1999 Opinion polling 116 seats needed for a majority

| Date_Released | Polling_institute | Socialist | Social_Democratic | Green_Communist | People_s_Party | Left_Bloc | Lead_ |
|---|---|---|---|---|---|---|---|
| October 10, 1999 | Election Results | 44.1% 115 seats | 32.3% 81 seats | 9.0% 17 seats | 8.3% 15 seats | 2.4% 2 seats | 11.8% |
| October 2, 1999 | Euroexpansão | 50.0% | 32.0% | 6.0% | 8.0% | 2.0% | 18.0% |
| October 1, 1999 | SEEDS | 47.0% | 32.0% | 8.0% | 7.0% | 1.0% | 15.0% |
| October 1, 1999 | Metris | 48.0% | 31.0% | 7.0% | 7.0% | 1.0% | 17.0% |
| October 1, 1999 | Universidade Católica | 47.2% | 30.0% | 7.9% | 7.2% | 2.8% | 17.2% |
| September 30, 1999 | Marktest | 46.2% | 30.7% | 10.6% | 4.2% | 2.8% | 15.5% |
| September 30, 1999 | Aximage | 49.0% | 33.0% | 7.0% | 6.0% | 1.0% | 16.0% |
| October 1, 1995 | 1995 election | 43.8% 112 seats | 34.1% 88 seats | 8.6% 15 seats | 9.1% 15 seats | — | 9.7% |