Mario De Clercq (born 5 March 1966) is a Belgian former racing cyclist.

In addition, De Clercq won the 2001 and 2002 Belgian National Cyclo-cross Championships.

Accused of being in possession of banned substances, along with Johan Museeuw and nine other riders, investigators visited their houses in 2003,[1] they faced an initial hearing in Kortrijk on 11 October 2005.

[2] De Clercq was due to stand trial on drug charges at a Belgian Court in 2006.

[5][6] De Clercq was found in possession of human growth hormone and Aranesp, a synthetic drug which increases red blood cell levels, which Museeuw obtained from Jose Landuyt.