Kristof Vliegen was born on June 22nd, 1982 in Maaseik, Belgium. He turned pro in 2001 and is yet to win a tournament on the ATP Tour. He has twice been a runner up on the tour. In 2006 he lost the final in Munich to Olivier Rochus. It was the first all Belgian final.

In the same year he reached three semi-finals in Chennai, Memphis and Halle. These performances helped him move up the world rankings. His best performance in a grand slam is the 3rd round which he achieved in the Australian Open in 2006.