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.
Chinese Taipei competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. "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 primarily due to opposition from the People's Republic of China. This also was the nation's eighth consecutive appearance at the Olympics.
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.
Malaysia 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, although it had previously competed in two other games under the name Malaya. Malaysia, however, did not participate at the 1980 Summer Olympics in Moscow, because of its partial support to the United States boycott.
Cuba competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's seventeenth appearance in the Olympics, except for some editions. Cuban athletes did not attend in two Olympic Games, where they joined the Soviet and North Korean boycott. Cuban Olympic Committee sent the nation's smallest delegation to the Games since 1972. A total of 151 athletes, 97 men and 54 women, competed in 18 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.
Laos competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's sixth appearance at the Olympics, having attended every edition of the Olympiad since 1980 except the 1984 Summer Olympics in Los Angeles, because of the Soviet boycott.
Israel competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. It was the nation's thirteenth appearance at the Summer Olympics.
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.
Trinidad and Tobago competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's sixteenth appearance at the Summer Olympics as an independent nation, although it had previously appeared in four editions as part of the British colony and the West Indies Federation. Trinidad and Tobago Olympic Committee sent a total of nineteen athletes to the Games, ten men and nine women, to compete only in track and field, shooting, swimming, and taekwondo, which made its Olympic debut; the nation's team size was relatively similar to the record in Sydney four years earlier.
Barbados competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This nation marked its ninth appearance at the Olympics, except the 1980 Summer Olympics in Moscow because of the United States boycott.
Bermuda 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 1980 Summer Olympics in Moscow.
Lesotho competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. It was the last time the nation competed under a former flag.
Grenada competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's sixth consecutive appearance at the Olympics.
Tunisia 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.
Yemen competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004.
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.
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.
Nepal competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004.
Libya, represented as Libyan Arab Jamahiriya, competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004.
