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.
Indonesia competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's twelfth appearance at the Olympics, excluding the 1964 Summer Olympics in Tokyo, and the 1980 Summer Olympics in Moscow because of the United States boycott. Krisna Bayu was originally the flag bearer, however the role was later done by Christian Hadinata because Bayu was suffering from flu at the eve of opening ceremony.
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.
Poland competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's eighteenth appearance at the Summer Olympics, except the 1984 Summer Olympics in Los Angeles, because of the Soviet boycott. The Polish Olympic Committee sent a total of 194 athletes to the Games, 132 men and 62 women, to compete in 21 sports. Men's volleyball was the only team-based sport in which Poland had its representation in these Olympic Games. There was only a single competitor in women's taekwondo.
Bulgaria competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's seventeenth appearance at the Summer Olympics, except for three occasions, including the 1984 Summer Olympics in Los Angeles, because of the Soviet boycott. The Bulgarian Olympic Committee sent 95 athletes, 49 men and 46 women, to compete in 19 sports. Shooting champion and four-time Olympian Mariya Grozdeva became the nation's first ever female flag bearer in the opening ceremony.
Romania competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. Romanian athletes have competed at every Summer Olympic Games since its official debut in 1924, missing only two editions, including the 1948 Summer Olympics. The Romanian Olympic and Sports Committee sent the nation's smallest team to the Games since the 1988 Summer Olympics in Seoul. A total of 108 athletes, 50 men and 58 women, had competed in 16 different sports, most notably in artistic gymnastics and rowing. For the third time in Olympic history, Romania was again represented by more female than male athletes.
Slovenia competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's fourth consecutive appearance at the Summer Olympics since the post-Yugoslav era. The Slovenian Olympic Committee sent the nation's largest ever delegation to the Games in Olympic history. A total of 79 athletes, 56 men and 23 women, competed in 10 sports. For the second consecutive time, men's handball was the only team-based sport in which Slovenia had its representation at these Games.
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.
Estonia competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's ninth appearance at the Summer Olympics.
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.
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.
Thailand competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's fifteenth appearance at the Olympics, except the 1980 Summer Olympics in Moscow because of its partial support to the United States boycott.
Chinese Taipei competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. "Chinese Taipei" was the designated name used by Taiwan to participate in some international organizations and almost all sporting events, including the Olympic Games. Neither the common name "Taiwan" nor the official name "Republic of China" would be used due primarily to opposition from the People's Republic of China. This was the nation's eighth consecutive appearance at the Olympics.
Algeria competed at the 2012 Summer Olympics in London, United Kingdom, from 27 July to 12 August 2012. This was the nation's twelfth consecutive appearance at the Summer Olympics, except for the 1976 Summer Olympics in Montreal because of the African boycott.
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.
Azerbaijan competed at the 2012 Summer Olympics in London, United Kingdom, from 27 July to 12 August 2012. This was the nation's fifth consecutive appearance at the Olympics in the post-Soviet era. The National Olympic Committee of the Azerbaijani Republic sent the nation's largest delegation to the Games. A total of 53 athletes, 39 men and 14 women, competed in 15 sports. There was only a single competitor in road cycling, equestrian show jumping, fencing, and shooting. The Azerbaijani athletes also included their only defending champion, judoka Elnur Mammadli, who became the nation's flag bearer at the opening ceremony.
Togo competed at the 2012 Summer Olympics in London, held from July 27 to 12 August 2012. This was the nation's ninth appearance at the Olympics, except the 1976 Summer Olympics in Montreal, and the 1980 Summer Olympics in Moscow because of the African and the United States boycott.
Niger competedwith six athletes in five sports at the 2012 Summer Olympics in London, held from 27 July to 12 August 2012. This was the nation's eleventh appearance at the Olympics, having competed at every Summer Olympics since 1964 with the exception of the 1976 Summer Olympics in Montreal, and the 1980 Summer Olympics in Moscow because of the African and the United States boycotts.
The African island country of Seychelles competed at the 2012 Summer Olympics in London, United Kingdom, held from 27 July to 12 August 2012. This was the nation's eighth appearance at the Olympics, except the 1988 Summer Olympics in Seoul because of its partial support to the North Korean boycott.
Myanmar competed at the 2012 Summer Olympics in London, held from 27 July to 12 August 2012. This was the nation's sixteenth appearance at the Olympics, although at most previous Games it competed under the name Burma. Myanmar did not participate at the 1976 Summer Olympics in Montreal for political reasons.
