| Date | 22 October 1968 — 10:00 | |
|---|---|---|
| Location | Alberca Olímpica Francisco Márquez, Ciudad de México | |
| Format | Fastest eight advanced to the final. | |
| Pos | Lane | Competitor | NOC | Time | ||
|---|---|---|---|---|---|---|
| 1 | 3 | Andrey Dunayev | URS | 5:01.9 | ||
| 2 | 5 | Martyn Woodroffe | GBR | 5:03.9 | ||
| 3 | 6 | Eduardo Alanís | MEX | 5:14.9 | ||
| 4 | 2 | Jacek Krawczyk | POL | 5:15.1 | ||
| 4 | José Martínez | CUB | – | |||
| – | Tony Asamli | PHI | – |
| Pos | Lane | Competitor | NOC | Time | ||
|---|---|---|---|---|---|---|
| 1 | 5 | Greg Buckingham | USA | 4:57.3 | ||
| 2 | 4 | Rafael Hernández | MEX | 5:01.1 | ||
| 3 | 2 | Hans Ljungberg | SWE | 5:06.1 | ||
| 4 | 7 | Vladimir Kravchenko | URS | 5:08.7 | ||
| 5 | 1 | Tomás Becerra | COL | 5:09.7 | ||
| 6 | 6 | Miguel Torres | ESP | 5:12.7 | ||
| 7 | 8 | Guðmundur Gíslason | ISL | 5:20.2 | ||
| 8 | 3 | Raúl Villagómez | MEX | 5:24.7 | ||
| – | Juan Carlos Bello | PER | – |
| Pos | Lane | Competitor | NOC | Time | ||
|---|---|---|---|---|---|---|
| 1 | 4 | Charlie Hickcox | USA | 4:56.2 | ||
| 2 | 7 | Reinhard Merkel | FRG | 5:00.6 | ||
| 3 | 1 | Bernhard Mock | FRG | 5:07.1 | ||
| 4 | 3 | Péter Lázár | HUN | 5:10.6 | ||
| 5 | 2 | Angel Chakarov | BUL | 5:10.9 | ||
| 6 | 6 | Ken Campbell | CAN | 5:19.6 | ||
| 7 | 8 | Gershon Shefa | ISR | 5:22.6 | ||
| 8 | 5 | Lee Tong-Shing | TPE | 5:50.0 |
| Pos | Lane | Competitor | NOC | Time | ||
|---|---|---|---|---|---|---|
| 1 | 1 | Mike Holthaus | FRG | 5:00.8 | ||
| 2 | 8 | George Smith | CAN | 5:04.4 | ||
| 3 | 5 | Yuliyan Rusev | BUL | 5:07.0 | ||
| 4 | 7 | Lars Kraus Jensen | DEN | 5:12.7 | ||
| 5 | 6 | Zbigniew Pacelt | POL | 5:18.6 | ||
| 6 | 3 | Raymond Terrell | GBR | 5:19.5 | ||
| 7 | 4 | Francisco Ramis | PUR | 5:30.9 | ||
| 8 | 2 | Antonio Cruz | GUA | 5:31.1 |
| Pos | Lane | Competitor | NOC | Time | ||
|---|---|---|---|---|---|---|
| 1 | 4 | Gary Hall | USA | 4:56.2 | ||
| 2 | 3 | Sandy Gilchrist | CAN | 4:57.5 | ||
| 3 | 6 | Karl Byrom | AUS | 5:11.9 | ||
| 4 | 2 | Michele D'Oppido | ITA | 5:16.4 | ||
| 5 | 7 | Jacques Henrard | BEL | 5:17.0 | ||
| 6 | 5 | Olle Ferm | SWE | 5:18.9 | ||
| – | Bob Loh | HKG | – | |||
| – | Amman Jalmaani | PHI | – |