The Carnival of Basel is the biggest carnival in Switzerland and takes place annually between February and March in Basel. It has been listed as one of the top fifty local festivities in Europe.

The Basler Fasnacht starts on the Monday after Ash Wednesday at precisely 4:00 am with the so-called Morgestraich. The carnival lasts for exactly 72 hours and, therefore, ends on Thursday morning at 4:00 am. During this time the Fasnächtler (the participants) dominate the old town of central Basel, running free in the streets and restaurants. Basler Fasnacht is often referred to as die drey scheenschte Dääg ("the three most beautiful days").

Unlike the Carnival celebrations held in other cities on the Rhine (such as those in Cologne, Mainz and Düsseldorf), the Basel Carnival displays a clear separation between participants and spectators.