The show brought together 150 producers of agricultural products, farm machinery and food who will be presenting their products until 3 October.
Expressing satisfaction with what was put on display at the fair, President Josipovic said the authorities should work on creating better economic, cultural and other conditions and on countering mafia-style crime.
"Reforms that will awaken optimism are necessary," the president said, adding that the state must create equal opportunities for everyone.
Sasa Uranjek, the director of the Osijek Sajam company which organised the event, said that the fair was taking place on 7,000 square metres of space.
Apart from Croatian exhibitors, also present are guests from Hungary and Serbia.