A non-binding referendum on the Single European Act was held in Denmark on 27 February 1986. It was approved by 56.2% of voters, with a voter participation of 75.4%.
The referendum was held by the government of the Prime Minister of Denmark, Poul Schlüter. The government was in favour of Denmark ratifying the Single European Act, but a majority in parliament was against it. The referendum was the last Europe-related referendum in which parties such as the Social Democrats and the Social Liberal Party recommended against ratification.
References
Danish Single European Act referendum, 1986 Wikipedia(Text) CC BY-SA