The eight are Australia, France, New Zealand, South Africa, England, Scotland, Wales and Argentina.
"The decision was taken in part as a result of the congested playing schedule and also because of the growing number of mismatches at the qualifying stage due to the difference in standards between professional and amateur teams," the IRB said.
Three teams were seeded for the 1999 World Cup - defending champions South Africa, losing 1995 finalists New Zealand and third place play-off winners France - and they were joined as automatic qualifiers by host nation Wales.
The eight quarter-finalists in 2003 will also qualify for the 2007 tournament, it said.
The lengthy regional qualification for the 1999 World Cup led to many unbalanced matches, particularly in the latter stages when top sides like England and Australia entered - England beat the Netherlands 110-0 in one qualifier.
Sixteen countries qualified for the 1999 finals, contested by 20 teams and won by Australia.
Twenty teams will also take part in the 2003 tournament including four from Europe, two from Oceania, two from the Americas, one from Africa and one from Asia. Two countries will also qualify as lucky losers from a repechage tournament.
The eight quarter-finalists from the 1999 World Cup will be granted automatic qualification for the 2003 tournament in Australia and New Zealand, the International Rugby Board said on Friday.
