204 countries or Participating National Olympic Committees were in the Olympics and 79 had athletes that won at least one medal. The names of the countries followed by number of athletes can be found in the related link for
Participants204
all of them
Brazil
205 countries are expected in Olympics 2012.
204
15
for a full list of all countries represented i suggest you look at the BBC website
200
4 Continents 305 Countries
204 countries were represented in the 2008 Summer Olympics.
An estimated 205 nations will/might take part in the Olympic Games in 2012
England America