This was the eleventh time the event was held, having appeared at every Olympics since the first in 1896. With a 12 year gap due to World War II, none of the athletes from the 1936 edition returned. Notable entrants and favorites were American Mel Patton and Panamanian Lloyd LaBeach. American Barney Ewell was a "top sprinter" but "felt to be slightly past his prime." The third member of the United States team was Harrison Dillard, a hurdles specialist who had also entered the 100 metres and came in third at the U.S. Olympic trials. Bermuda, Burma, Guyana, Iraq, Jamaica, Pakistan, Panama, Trinidad and Tobago, and Uruguay were represented in the event for the first time. The United States was the only nation to have appeared at each of the first eleven Olympic men's 100 metres events.
Competition format
The event retained the four round format from 1920–1936: heats, quarterfinals, semifinals, and a final. There were 12 heats, of 4–7 athletes each, with the top 2 in each heat advancing to the quarterfinals. The 24 quarterfinalists were placed into 4 heats of 6 athletes. The top 3 in each quarterfinal advanced to the semifinals. There were 2 heats of 6 semifinalists, once again with the top 3 advancing to the 6-man final.
Records
Prior to the competition, the existing world and Olympic records were as follows.
The fastest two runners in each of the twelve heats advanced to the second round. Official hand-timed results are known only for the top three in each heat; unofficial auto-timed results are shown in parentheses.
Heat 1
Rank
Athlete
Nation
Time
Notes
1
Barney Ewell
10.5
2
Alastair McCorquodale
10.5
3
Leslie Laing
11.0
4
Angel García
5
Nestor Jacono
–
Bogdan Lipski
Heat 2
Rank
Athlete
Nation
Time
Notes
1
Mel Patton
10.6
2
Ivan Hausen
10.9
3
James O'Brien
10.9
4
Fernando Lapuente
5
Hector Gosset
6
Guillermo Rodríguez
Heat 3
Rank
Athlete
Nation
Time
Notes
1
Lloyd La Beach
10.5
2
Béla Goldoványi
11.0
3
Frank Mahoney
11.8
–
George Rhoden
–
Tomás Paquete
–
John De Saram
Heat 4
Rank
Athlete
Nation
Time
Notes
1
Juan López
10.5
2
Ken Jones
10.6
3
Jan Meijer
11.0
4
Máximo Reyes
5
Finnbjörn Þorvaldsson
–
Kyros Marinis
Heat 5
Rank
Athlete
Nation
Time
Notes
1
Harrison Dillard
10.4
2
Aroldo da Silva
10.6
3
Peter Bloch
11.1
4
Pol Braekman
–
Ricardo Sáenz
–
John O'Donnell
Heat 6
Rank
Athlete
Nation
Time
Notes
1
McDonald Bailey
10.5
2
Haukur Clausen
11.0
3
Abram van Heerden
11.1
4
Carlos Silva
5
Bernabe Lovina
6
Stanley Lines
Heat 7
Rank
Athlete
Nation
Time
Notes
1
John Treloar
10.5
2
René Valmy
10.8
3
György Csányi
11.1
4
Carlos Isaac
5
Sayed Moukhtar
6
Ali Salman
–
Jack Parry
Heat 8
Rank
Athlete
Nation
Time
Notes
1
Rafael Fortún
10.7
2
John Bartram
10.8
3
Basil McKenzie
10.8
4
Hélio da Silva
5
Jo Zwaan
–
Duncan White
Heat 9
Rank
Athlete
Nation
Time
Notes
1
Morris Curotta
10.7
2
Gerardo Bönnhoff
10.8
3
Raúl Mazorra
11.1
4
Örn Clausen
5
Raşit Öztaş
-
Perry Johnson
Heat 10
Rank
Athlete
Nation
Time
Notes
1
George Lewis
10.8
2
Ted Haggis
10.9
3
Walter Pérez
11.0
4
Santiago Ferrando
5
Stefanos Petrakis
–
Joseph Stéphan
Heat 11
The tailwind of 3.3 m/s made this heat ineligible for records purposes.
The fastest three runners in each of the four heats advanced to the semifinal round. Official hand-timed results are known only for the top three in each heat; unofficial auto-timed results are shown in parentheses.
Quarterfinal 1
Rank
Athlete
Nation
Time
Notes
1
Harrison Dillard
10.4
2
Juan López
10.6
3
Ken Jones
10.7
4
Ivan Hausen
5
Ted Haggis
6
António Morais
Quarterfinal 2
Rank
Athlete
Nation
Time
Notes
1
Barney Ewell
10.5
2
McDonald Bailey
10.6
3
Morris Curotta
10.8
4
George Lewis
5
Béla Goldoványi
6
Haukur Clausen
Quarterfinal 3
Rank
Athlete
Nation
Time
Notes
1
Mel Patton
10.4
2
Alastair McCorquodale
10.5
3
John Bartram
10.6
4
René Valmy
5
Mario Fayos
6
Isidoor Van De Wiele
Quarterfinal 4
Rank
Athlete
Nation
Time
Notes
1
Lloyd La Beach
10.5
2
John Treloar
10.5
3
Rafael Fortún
10.6
4
Aroldo da Silva
5
Gerardo Bönnhoff
6
Eric Prabhakar
Semifinals
The fastest three runners in each of the two heats advanced to the final round. Official hand-timed results are known only for the top three in each heat; unofficial auto-timed results are shown in parentheses.
Semifinal 1
Rank
Athlete
Nation
Time
Notes
1
Harrison Dillard
10.5
2
Barney Ewell
10.5
3
Alastair McCorquodale
10.7
4
John Bartram
5
Juan López
6
Morris Curotta
Semifinal 2
Rank
Athlete
Nation
Time
Notes
1
Mel Patton
10.4
2
Lloyd LaBeach
10.5
3
McDonald Bailey
10.6
4
John Treloar
5
Rafael Fortún
6
Ken Jones
Final
Patton "got off to a disastrous start and was not a factor." Dillard led the entire way. Official hand-timed results are known only for the top three in each heat; unofficial auto-timed results are shown in parentheses.