The Zagreb Open was a professional tennis tournament played on outdoor red clay courts. It was part of the Association of Tennis Professionals (ATP) Challenger Tour and the International Tennis Federation (ITF) Women's Circuit. It was held annually at the Sportski Park Mladost in Zagreb, Croatia, from 1996 to 2011. Tom Vanhoudt is the doubles record holder with two titles, along with Ágnes Szávay on the women's counterpart.