The Zagreb Open is a professional tennis tournament played on outdoor red clay courts. It is part of the ATP Challenger Tour and of the ITF Women's World Tennis Tour. It was held annually at the Sportski park Mladost in Zagreb, Croatia, from 1996 to 2011. The men's tournament returned in 2021 and was played for two years at the Tenis centar Maksimir. After another break in 2023 the tournament moved in 2024 to the Sportsko rekreacijski centar à  alata. The women's tournament returned in 2024, played also at the SRC à  alata.
Tom Vanhoudt is the doubles record holder with two titles, along with ÃÂgnes Szávay on the women's counterpart with one single and one doubles title.