Japan competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. Japanese athletes have competed at every Summer Olympic Games in the modern era since 1912 except for two editions; it was not invited to the 1948 Summer Olympics in London for its role in World War II, and was also part of the US-led boycott of the 1980 Summer Olympics in Moscow. The Japanese Olympic Committee sent a total of 306 athletes, 139 men and 167 women, to compete in 27 sports. For the first time in its Olympic history, Japan was represented by more female than male athletes.
Kazakhstan competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's third appearance at the Summer Olympics in the post-Soviet era.
Ukraine competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's third consecutive appearance at the Summer Olympics in the post-Soviet era. The National Olympic Committee of Ukraine sent the nation's largest ever delegation to these Games. A total of 240 athletes, 125 men and 115 women, took part in 21 sports. Women's handball was the only team-based sport in which Ukraine had its representation at these Games for the first time. There was only a single competitor in modern pentathlon and taekwondo.
Russia competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's third consecutive appearance at the Summer Olympics as an independent nation. The Russian Olympic Committee sent a total of 446 athletes to the Games, 244 men and 202 women, to compete in all sports, except baseball, field hockey, football, and softball.
Belarus competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's fifth appearance at the Summer Olympics in the post-Soviet era. The Belarus Olympic Committee sent a total of 151 athletes to the Games, 82 men and 69 women, to compete in 22 sports.
Czech Republic competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's third appearance at the Summer Olympics after gaining its independence from the former Czechoslovakia. The Czech Olympic Committee sent the nation's largest team to the Games since the post-Czechoslovak era. A total of 142 athletes, 80 men and 62 women, competed in 19 sports; the nation's team size was roughly denser from Sydney by one sixth of the athletes. Women's basketball was the only team-based sport in which the Czech Republic had its representation at these Olympic Games. There was only a single competitor in equestrian, artistic and trampoline gymnastics, judo, and weightlifting.
Slovakia competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's third consecutive appearance at the Summer Olympics since the post-Czechoslovak era. The Slovak Olympic Committee sent a total of 64 athletes to the Games, 48 men and 16 women, to compete in 11 sports. There was only a single competitor in artistic and trampoline gymnastics and sailing.
Uzbekistan competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's third consecutive appearance at the Olympics. The National Olympic Committee of the Republic of Uzbekistan sent a total of 70 athletes to the Games, 52 men and 18 women, to compete in 13 different sports, tying its delegation record with Sydney four years earlier. There was only a single competitor in road cycling, artistic and trampoline gymnastics, and table tennis.
The Russian Federation competed at the 2008 Summer Olympics, held in Beijing, China, represented by the Russian Olympic Committee. Russia competed in all sports except baseball, football, field hockey, softball and taekwondo.
Belarus attended the 2008 Summer Olympics in Beijing, China. A team of 181 athletes competed in 28 different sports.
Belarus competed at the 2012 Summer Olympics in London, United Kingdom, from 27 July to 12 August 2012. This was the nation's fifth appearance at the Summer Olympics in the post-Soviet era. The Belarus Olympic Committee sent a total of 166 athletes to the Games, 90 men and 76 women, to compete in 20 sports.
Hungary competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. Hungarian athletes have competed at every Summer Olympic Games in the modern era, except the 1920 Summer Olympics in Antwerp, and the 1984 Summer Olympics in Los Angeles because of the Soviet boycott. The Hungarian Olympic Committee sent the nation's smallest delegation to the Games since 1956. A total of 159 athletes, 97 men and 62 women, competed in 18 sports.
Ukraine competed at the 2012 Summer Olympics in London, from July 27 to August 12, 2012. This was the nation's fifth consecutive appearance at the Summer Olympics in the post-Soviet era. The National Olympic Committee of Ukraine sent a total of 238 athletes, split equally between men and women, to compete in 21 sports.
Bulgaria competed at the 2012 Summer Olympics in London, United Kingdom from 27 July to 12 August 2012. It was the nation's nineteenth appearance at the Summer Olympics, having missed the Olympics on three occasions, including the 1984 Summer Olympics in Los Angeles because of the Soviet boycott. Despite this being London's third Olympic Games, this was the first time a Bulgarian team appeared at a London Olympics. The Bulgarian Olympic Committee sent the nation's smallest delegation to the Games, tying the record with Helsinki in 1952, and with Tokyo in 1964. A total of 63 athletes, 36 men and 27 women, competed in 16 sports. Men's volleyball was the only team event in which Bulgaria was represented in these Olympic games. There was only a single competitor in badminton, sprint canoeing, fencing, and judo.
Cuba competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's nineteenth appearance in the Olympics. With baseball's removal from the Olympic program and the absence of the nation's volleyball team for the first time, the Cuban Olympic Committee sent the nation's smallest delegation to the Games since 1964. A total of 111 athletes, 66 men and 45 women, competed in 13 sports. There was only a single competitor in archery and table tennis.
Romania competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This nation has competed at the Summer Olympic Games since its official debut in 1924, missing only two editions, including the 1948 Summer Olympics. Despite being London's third Olympic Games, this is the first time the Romanian team has competed in London. The Romanian Olympic and Sports Committee sent a total of 103 athletes to the Games, 54 men and 49 women, to compete in 14 sports.
Ukraine competed at the 2016 Summer Olympics in Rio de Janeiro, Brazil, from 5 to 21 August 2016. This was the nation's sixth consecutive appearance at the Summer Olympics in the post-Soviet era.
Armenia competed at the 2016 Summer Olympics in Rio de Janeiro, Brazil, from 5 to 21 August 2016. It was the nation's sixth consecutive appearance at the Summer Olympics in the post-Soviet era.
Haiti competed at the 2016 Summer Olympics in Rio de Janeiro, Brazil, from 5 to 21 August 2016. It was the nation's sixteenth appearance at the Summer Olympics since its debut in 1900.
Uzbekistan competed at the 2020 Summer Olympics in Tokyo. Originally scheduled to take place from 24 July to 9 August 2020, the Games were postponed to 23 July to 8 August 2021, due to the COVID-19 pandemic. It was the nation's seventh consecutive appearance at the Summer Olympics in the post-Soviet era.
Russian Empire (1900–1912)
Soviet Union (1952–1988)
Unified Team (1992)
