Swimming at the 2009 World Aquatics Championships – Men's 100 metre backstroke

The men's 100 metre backstroke at the 2009 World Championships took place Monday 27 July (prelims and semifinals) and on the evening of Tuesday 28 July (final) at the Foro Italico in Rome, Italy.

Records
Prior to this competition, the existing world and competition records were as follows:

The following records were established during the competition: