The National Farmers' Union (NFU) has voted that farmers' interests are best served by remaining in the EU.
A resolution passed by the organisation's council said the decision was made "on the balance of existing evidence available to us at present".
Meurig Raymond, president of the NFU, said a survey of members suggests 20% support Brexit, while 35% to 50% support remaining within the EU. The rest have not made up their minds.
The NFU, which represents farmers across England and Wales, said it would not tell its 55,000 members how to vote in the June 23 referendum, and will not be actively campaigning.
Vote Leave has so far said little about the Chancellor's gloomy predictions for Brexit, but Leave.EU thinks it's still a price worth paying.
The Treasury forecasts leaving the EU would leave households quite a lot poorer on average - between £2600 and £5200 a year in 15 years.
George Osborne's comments in The Times come ahead of a Treasury report on cost to the country of pulling out of the EU.