He also represented the Netherlands in the Eisenhower Trophy in 1990 and 1992 before quitting his law and psychology studies at Leiden University to turn professional in 1993.

Muntz began his career on the second tier Challenge Tour in 1994, finishing 13th on the end of season rankings, and picking up his first title.

In 1999 Muntz came close to his first European Tour victory when he lost to Warren Bennett in a play-off for the Scottish PGA Championship.

The following season he won the Qatar Masters to become the first Dutchman to win a European Tour event since the tour was founded in 1972 and the first to win a top level European professional tournament since Joop Rühl won the 1947 Dutch Open.

European Tour playoff record (0–1) Note: Muntz never played in the U.S. Open or the PGA Championship.