Poland subsequently joined the European Union that year following the ratification of the Treaty of Accession 2003.

The biggest opposition party, the Civic Platform, was also strongly supportive of joining the EU.

The agrarian Polish People's Party gave its support to the "Yes" campaign after its demands for the government were met in regards to farmers.

The radical agrarian Self-Defence of the Republic of Poland was strongly Eurosceptic since its foundation but ultimately stayed neutral during the campaign.

[2] Note: The table lists the political parties which were represented in the Sejm at the time of the referendum.