Swimming at the 2019 Pan American Games – Men's 100 metre butterfly

Prior to this competition, the existing world and Pan American Games records were as follows:

World record	Caeleb Dressel (USA)	49.50	Gwangju, South Korea	July 26, 2019
Pan American Games record	Giles Smith (USA)	52.04	Toronto, Canada	July 16, 2015

The first round was held on August 7.^[2][3][4][5]

Rank	Heat	Lane	Name	Nationality	Time	Notes
1	2	4	Luis Martínez	Guatemala	51.44	QA, GR, NR
2	2	5	Santiago Grassi	Argentina	51.92	QA
3	3	5	Matthew Josa	United States	52.28	QA
4	3	4	Vinicius Lanza	Brazil	53.11	QA
5	1	4	Tom Shields	United States	53.29	QA
6	3	6	Ben Hockin	Paraguay	53.43	QA
7	1	5	Long Gutiérrez	Mexico	54.05	QA
8	2	6	David Arias	Colombia	54.16	QA
9	1	3	Roberto Strelkov	Argentina	54.18	QB
10	3	3	Esnaider Reales	Colombia	54.19	QB
11	2	3	Mateo González Medina	Mexico	54.37	QB
12	1	6	Bryan Chavez Avendaño	Venezuela	54.85	QB
13	2	1	Javier Tang Juy	Peru	55.47	QB
14	3	2	Kael Yorke	Trinidad and Tobago	55.53	QB
15	2	2	N'Nhyn Fernander	Bahamas	55.65	QB
16	2	7	Bryan Alvaréz	Costa Rica	55.80	QB
17	1	7	Carlos Vasquez Moreno	Honduras	56.01
18	1	2	Gabriel Araya	Chile	56.13
19	3	1	Lázaro Martín Vergara	Cuba	56.17
20	1	1	Gustavo Gutierrez Lozano	Peru	56.20
21	3	7	Adriel Sanes	Virgin Islands	56.46
22	2	8	Lleyton Martin	Antigua and Barbuda	58.28
23	3	8	Jesse Washington	Bermuda	58.54

The B final was also held on August 7.^[6]

Rank	Lane	Name	Nationality	Time	Notes
9	4	Roberto Strelkov	Argentina	54.04
10	3	Mateo González Medina	Mexico	54.09
11	5	Esnaider Reales	Colombia	54.30
12	6	Bryan Chavez Avendaño	Venezuela	54.82
13	8	Bryan Alvaréz	Costa Rica	55.50
14	1	N'Nhyn Fernander	Bahamas	55.71
15	7	Kael Yorke	Trinidad and Tobago	55.90
16	2	Javier Tang Juy	Peru	56.06

The A final was also held on August 7.^[7]

Rank	Lane	Name	Nationality	Time	Notes
	2	Tom Shields	United States	51.59
	4	Luis Martínez	Guatemala	51.63
	6	Vinicius Lanza	Brazil	51.88
4	5	Santiago Grassi	Argentina	52.15
5	3	Matthew Josa	United States	52.22
6	1	Long Gutiérrez	Mexico	53.67
7	7	Ben Hockin	Paraguay	53.70
8	8	David Arias	Colombia	54.06