With 30 kilometres to go Christophe Mengin and Fabio Baldato tried to escape without success but leading to an important move by Tom Boonen, Juan Antonio Flecha and George Hincapie, with the late addition of Leif Hoste.

While they were being captured, 2003 winner Peter Van Petegem suffered a puncture and effectively saw his chances of a repeat victory annulled.

In the famous cobblestone section Carrefour de l'Arbre (with 15 kilometres to Roubaix) Museeuw made a series of accelerations which reduced the leading group to Museeuw himself, Magnus Bäckstedt, Roger Hammond, Tristan Hoffman, Fabian Cancellara and George Hincapie, who lost contact soon afterwards but who would hang-on to finish 8th.

The four riders in front entered the velodrome with Cancellara leading the group, but it was Magnus Bäckstedt who won the sprint ahead of Hoffman, Hammond and the Swiss.

This 2004 edition of Paris–Roubaix was the last to be ridden by three-time winner Johan Museeuw, who crossed the finish line hand-in-hand with his compatriot and rival Peter Van Petegem (the previous year's champion).