Swimming at the 1998 World Aquatics Championships – Men's 100 metre butterfly

The finals and the qualifying heats of the men's 100 metre butterfly event at the 1998 World Aquatics Championships were held on Friday 1998-01-16 in Perth, Western Australia.

Qualifying heats
Note: This is not a complete list of results. The SwimNews source below lists 70 swimmers entered in the event. One of the non-list swimmers is very likely Kamal Salman Masud who set a Pakistan Record of 58.19.