The Waikato Rodeo was cancelled on Saturday, having earlier been postponed on February 18.
Association secretary Shelly Patterson said she had never experienced the event being rained off in the 10 years she has been secretary, while long serving past president Kevin Marshall can only recall it ever being cancelled twice previously.
"We were left with little option after the relentless rain that fell - public and animal safety is paramount.
"We had no alternative but to pull the plug," said Patterson.
"We are hugely disappointed but are now looking forward to the 2018 Waikato Rodeo taking place at Kihikihi."