The 2015 edition of E3 Harelbeke was in length. It started in the Belgian municipality of
Harelbeke, where there was a neutral zone before the official start. Initially, the route headed north, but after a short distance it turned south-east to reach the town of
Avelgem after . The route then turned north-east through
Oudenaarde and reached the first climb, the Katteberg, after . The route briefly went south-east again to reach the second climb, the Leberg, later. Between the Katteberg and the Leberg, there were two flat sections of
cobbles, the Holleweg and the Haaghoek. The race then entered a long loop without any significant climbs, though it did include the Paddestraat, another flat section of cobbles. This loop first went north-east, reaching
Burst after , then south to . The loop turned west at this point, travelling through
Geraardsbergen after . The third climb came after at La Houppe. This was the longest climb of the day at in length. The course then turned north to reach the Berg Stene climb after . The next four climbs came in quick succession over the next : the Boigneberg, the Eikenberg (the first of the cobbled climbs), the Stationberg and the Taaienberg. A flat section followed, as the course travelled south-west through
Ronse, before a turn to the north to tackle the next climb. This was the Knokteberg, which came after , and it was followed by another turn to the east and the climb of the Hotondberg after . The Rotelenberg (after ) and the Kortekeer (after ) were the next two climbs as the route again approached Oudenaarde. After turning south at , there were remaining. With remaining, the riders climbed the Kapelberg. The next section was expected to be the key part of the race: the climbs of the Paterberg and the
Oude Kwaremont. The Oude Kwaremont was the final cobbled climb of the day; at the top of the climb there were left to the end of the race. In past editions of the race this was the section where a decisive breakaway was formed; the combination of the two climbs was also a major feature of the
Tour of Flanders. The route continued south to the penultimate climb of the day, the Karnemelkbeekstraat, with remaining, then turned north-west for the final part of the race. This section was mostly flat; the only climb was the Tiegemberg with to the finish line. It was expected that riders dropped in the hilly section of the course would try to regain contact on this section. The route continued west and finished where it had started in Harelbeke. == Teams ==