The event was named after Giancarlo Zigante, a local truffle hunter who made it into the Guinness World Records for finding the world's biggest truffle.
Every year the event at Livade attracts more and more visitors, and this year more than 35,000 truffle lovers and tourists from all over the world are expected to visit the fair.
Attending the opening ceremony, among others, were Assistant Agriculture Minister Marija Vuckovic and Istria County head Valter Flego.
Flego said that truffles, which are the most expensive subterranean fungus in the world, were the reason why many young families decided to stay in the rural part of Istria.
This year's fair has brought together more than 50 truffle hunters and producers of wine, olive oil, smoked ham, cheese, honey and other regional delicacies.
Truffle lovers will be able to attend numerous food tastings and cooking workshops as well as visit the Motovun forest, the best known truffle habitat in Croatia.