Organisers of the Southern Field Days are looking for a record attendance of up to 40,000 people this year.
The biennial field days open at Waimumu, near Gore, on Wednesday and run until Friday.
When it started in 1982 there were just 54 exhibitors but that has risen to 790 - all under cover and able to sustain four seasons of weather.
Southern Field Days chair Mark Dillon has been involved with the event for 15 years.
"It's the place to be seen. If you're not here people ask 'well why aren't you at the field days'," he said.
"There's a lot of guys spend a lot of time and money transporting machinery here and they tell us generally after most events that they've had great success and sometimes sold everything on their site."
One of the significant areas of growth was dairy exhibits, which for the first time this year would include a live display of robotic milking.
"Now with the change from sheep and beef to more dairying, there's more associated businesses that go along with the dairying side of it," Mr Dillon said.
About 33,000 people attended the last Southern Field Days two years ago, and organisers this year expect to crack the 40,000 mark.