An institutional referendum (Italian: referendum istituzionale, or referendum sulla forma istituzionale dello Stato) was held in Italy on 2 June 1946, a key event of Italian contemporary history.

Until 1946, Italy had been a kingdom ruled by the House of Savoy, reigning royal house of Italy since the national unification in 1861 and previously rulers of the Duchy of Savoy. However, in 1922 the rise of Benito Mussolini and the creation of the fascist regime, which eventually resulted in engaging Italy in World War II alongside Nazi Germany, considerably weakened the role of the monarchy.

Following the civil war and the Liberation from foreign troops in 1945, a popular referendum on the institutional form of the state was called and resulted in voters choosing the replacement of the monarchy with a republic. A Constituent Assembly was elected on the same day.