These are the results (medal winners) of the swimming competition at the 1978 World Aquatics Championships held in the city of West Berlin between August 20 and August 28.
| 100 m freestyle | 50.24 CR | 50.73 | 50.79 | ||||
| 200 m freestyle | 1:51.02 CR | 1:51.10 | 1:51.33 | ||||
| 400 m freestyle | 3:51.94 CR | 3:53.42 | 3:53.97 | ||||
| 1500 m freestyle | 15:03.99 CR | 15:20.77 | 15:23.38 | ||||
| 100 m backstroke | 56.36 CR | 56.69 | 58.01 | ||||
| 200 m backstroke | 2:02.16 | 2:03.71 | 2:03.90 | ||||
| 100 m breaststroke | 1:03.56 CR | 1:03.60 | 1:03.62 | ||||
| 200 m breaststroke | 2:18.37 | 2:18.42 | 2:20.16 | ||||
| 100 m butterfly | 54.30 | 55.26 | 55.38 | ||||
| 200 m butterfly | 1:59.38 CR | 1:59.80 | 2:01.33 | ||||
| 200 m individual medley | 2:03.65 WR | 2:04.99 | 2:05.29 | ||||
| 400 m individual medley | 4:20.05 WR | 4:22.29 | 4:27.04 | ||||
| 4 × 100 m freestyle relay | Jack Babashoff Rowdy Gaines Jim Montgomery David McCagg | 3:19.74 WR | Andreas Schmidt Ulrich Temps Peter Knust Klaus Steinbach | 3:26.65 | Per Holmertz Dan Larsson Per-Ola Quist Per-Alvar Magnusson | 3:26.95 | |
| 4 × 200 m freestyle relay | Bruce Furniss Bill Forrester Bobby Hackett Rowdy Gaines | 7:20.82 WR | Sergey Rusin Andrey Krylov Vladimir Salnikov Sergey Kopliakov | 7:28.41 | Andreas Schmidt Peter Knust Karsken Lippmann Frank Wennmann | 7:33.29 | |
| 4 × 100 m medley relay | Bob Jackson Nick Nevid Joe Bottom David McCagg | 3:44.63 CR | Klaus Steinbach Walter Kusch Michael Kraus Andreas Schmidt | 3:48.58 | Gary Abraham Duncan Goodhew John Mills Martin Smith | 3:49.06 |
| 100 m freestyle | 55.68 CR | 56.82 | 56.85 | ||||
| 200 m freestyle | 1:58.53 WR | 1:59.78 | 2:01.76 | ||||
| 400 m freestyle | 4:06.28 WR | 4:07.15 | 4:07.73 | ||||
| 800 m freestyle | 8:24.94 CR | 8:29.35 | 8:32.60 | ||||
| 100 m backstroke | 1:02.55 CR | 1:03.18 | 1:03.43 | ||||
| 200 m backstroke | 2:11.93 WR | 2:14.07 | 2:14.23 | ||||
| 100 m breaststroke | 1:10.31 WR | 1:10.77 | 1:11.99 | ||||
| 200 m breaststroke | 2:31.42 WR | 2:32.69 | 2:33.60 | ||||
| 100 m butterfly | 1:00.20 CR | 1:00.26 | 1:01.82 | ||||
| 200 m butterfly | 2:09.87 WR | 2:11.30 | 2:12.63 | ||||
| 200 m individual medley | 2:14.07 WR | 2:14.98 | 2:15.99 | ||||
| 400 m individual medley | 4:40.83 WR | 4:47.52 | 4:48.56 | ||||
| 4 × 100 m freestyle relay | 3:43.43 WR | Heike Witt Caren Metschuck Barbara Krause Petra Priemer | 3:47.37 | Gail Amundrud Nancy Garapick Sue Sloan Wendy Quirk | 3:49.59 | ||
| 4 × 100 m medley relay | Linda Jezek Tracy Caulkins Joan Pennington Cynthia Woodhead | 4:08.21 CR | Birgit Treiber Ramona Reinke Andrea Pollack Barbara Krause | 4:09.13 | Elena Kruglova Yuliya Bogdanova Irina Aksenova Larisa Tsaryova | 4:14.91 |