A referendum was held in Ontario, Canada on April 18, 1921, concerning a ban on the importation of alcoholic beverages into the province.

[1] Though the Judicial Committee of the Privy Council had ruled in 1896 that provinces do not have the authority to prohibit the importation of alcohol, the Canada Temperance Act allowed the federal government to enact a prohibition if a majority was reached in a referendum.

Similar referendums had previously been undertaken in Alberta, Manitoba, Saskatchewan and Nova Scotia in 1920, and in New Brunswick and Prince Edward Island in 1921.

[2] Initially, the Ontario referendum was to be held on the same day as those in Alberta, Manitoba, Saskatchewan and Nova Scotia.

Though the provincial government was bound by the results, the enactment of an importation ban would be delayed.