20. Unless you mean the gay rugby World Cup which involves 12.
Less. There are 20 countries.
The IRB (international rugby board) recognises 94 countries in the world in their world rankings.
There are over 100 countries for represented in world rugby
There are 32 countries participating in the World Cup 2010
There are 20 countries taking part in the rugby world cup 2011.
The only South American team participating in the 2011 Rugby World Cup is the nation of Argentina.
You can see the flags of all the countries participating in the FIFA World Cup 2010 in the related link.
nearly 30 countries.