Mexico competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's twentieth appearance at the Olympics, since its debut in 1900. Comité Olímpico Mexicano sent the nation's largest delegation to the Games since 1992. A total of 109 athletes, 59 men and 50 women, competed in 20 sports. Football was the only team-based sport in which Mexico had its representation in these Olympic Games. There was only a single competitor in fencing, shooting, and weightlifting.
Chile competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004.
Peru competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's fifteenth appearance at the Olympics, except the 1952 Summer Olympics in Helsinki.
Colombia competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's sixteenth appearance at the Olympics, except the 1952 Summer Olympics in Helsinki.
Argentina competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's twenty-first appearance at the Olympic Games, except for three different editions. Argentina did not attend the 1904 Summer Olympics in St. Louis, the 1912 Summer Olympics in Stockholm, and the 1980 Summer Olympics in Moscow, because of its support for the United States-led boycott. The sailor Carlos Espínola was the nation's flag bearer at the opening ceremony. 152 competitors, 106 men and 46 women, took part in 86 events in 22 sports.
The Dominican Republic competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. Francia Jackson was chosen to be the flag bearer at the games instead of the previous chosen athlete Félix Sánchez, who won the nation's first ever Olympic gold medal.
Paraguay competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's ninth appearance at the Olympics, except the 1980 Summer Olympics in Moscow because of its partial support to the United States boycott.
Monaco competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004.
Ecuador competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's tenth consecutive appearance at the Olympics, although it had first competed at the 1924 Summer Olympics in Paris.
Uruguay competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's eighteenth appearance at the Olympics, except the 1980 Summer Olympics in Moscow, because of its full support to the United States boycott.
Senegal competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's eleventh appearance at the Olympics.
Mauritania competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. The country's participation at Athens marked its sixth appearance in the Summer Olympics since its debut in the 1984 Summer Olympics. The delegation included two track and field athletes, Youba Hmeida and Aminata Kamissoko, who were both selected by wildcards after both failed to meet either the "A" or "B" qualifying standards. Hmeida was selected as the flag bearer for the opening ceremony. Neither of the Mauritanians progressed beyond the heats.
Panama competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's fourteenth appearance at the Olympics since its debut in 1920. Panama did not compete on four occasions, including the 1980 Summer Olympics in Moscow, because of its partial support of the United States boycott.
Morocco competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's eleventh appearance at the Olympics, except the 1980 Summer Olympics in Moscow, because of its partial support to the United States boycott.
Paraguay competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's eleventh appearance at the Olympics, except the 1980 Summer Olympics in Moscow because of its partial support to the United States boycott.
Ecuador competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's twelfth consecutive appearance at the Olympics. It had first competed at the 1924 Summer Olympics in Paris.
Peru competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's seventeenth appearance at the Olympics, having only missed the 1952 Summer Olympics in Helsinki.
El Salvador competed at the 2012 Summer Olympics in London, United Kingdom, from 27 July to 12 August 2012. This was the nation's tenth appearance at the Olympics.
Costa Rica competed at the 2012 Summer Olympics in London from 27 July to 12 August 2012. This was the nation's fourteenth appearance at the Olympics, excluding four occasions from its national debut in 1936.
El Salvador competed at the 2016 Summer Olympics in Rio de Janeiro, Brazil, from 5 to 21 August 2016. This was the nation's eleventh appearance at the Summer Olympics, although it first competed in 1968.
