The exhibition was organised by Vinistra, the association of winegrowers and winemakers of Istria.
In evaluating wines for this year's show, a record 69 gold medals were awarded for Malvasia wines and 24 for Teran wines.
"This year's evaluation showed the extraordinary potential of Istrian winemakers and of Istria as a winegrowing region, with the largest number of wine samples entered for the competition to date," Vinistra president Nikola Benvenuti said at the opening ceremony.
The exhibition is accompanied by a food programme that will present numerous restaurants, and there will also be several wine and food tasting events.
This year's exhibition partner is the Swedish wine tasting organisation, Munskankarna, which has declared Istria the Wine Region of 2017.
Among those attending were the president of the Croatian Employers' Association, Gordana Deranja, assistant agriculture minister Kresimir Ivancic, Istria County head Valter Flego, and British wine writer and television presenter Oz Clarke.
The exhibition closes on May 14.