The Polish referendum on the Treaty establishing a Constitution for Europe is a referendum expected to be held on in October 2005 to decide whether Poland should ratify the proposed Constitution of the European Union.

Poland was enthusiastic about joining the EU but scepticism about the Constitution is widespread due to a feeling that the country had lost out on voting weights issue during negotiations. President Aleksander Kwasniewski has said that a referendum on the Constitution may be combined with presidential elections in October 2005. It will be legally binding but will require a turnout of at least half the electorate to be valid.