The 1999 election was the first election for the European Parliament after the enlargement of the European Union with Austria, Finland and Sweden. The voter turn-out was generally low, except in Belgium and Luxembourg, where voting is compulsory and where national elections were held that same day. The next election was held in 2004 (see European Parliament Election 2004).
| Country | AT | BE | DE | DK | ES | FI | FR | GR | IE | IT | LU | NL | PT | SE | UK | Total |
| Party | ||||||||||||||||
| EPP/ED | 7 | 6 | 53 | 1 | 28 | 5 | 21 | 9 | 5 | 34 | 2 | 9 | 9 | 7 | 37 | 233 |
| PES | 7 | 5 | 33 | 3 | 24 | 3 | 22 | 9 | 1 | 17 | 2 | 6 | 12 | 6 | 30 | 180 |
| ELDR | 5 | 6 | 3 | 5 | 1 | 8 | 1 | 8 | 4 | 10 | 51 | |||||
| Greens/EFA | 2 | 7 | 7 | 4 | 2 | 9 | 2 | 2 | 1 | 4 | 2 | 6 | 48 | |||
| EUL/NGL | 6 | 1 | 4 | 1 | 11 | 7 | 6 | 1 | 2 | 3 | 42 | |||||
| UEN | 1 | 13 | 6 | 9 | 2 | 31 | ||||||||||
| EDD | 4 | 6 | 3 | 3 | 16 | |||||||||||
| N.I. | 5 | 2 | 1 | 5 | 11 | 1 | 25 | |||||||||
| Total | 21 | 25 | 99 | 16 | 64 | 16 | 87 | 25 | 15 | 87 | 6 | 31 | 25 | 22 | 87 | 626 |