Piirissaar is an Estonian island located in Lake Peipus. It is located in Tartu County and is administered as part of Tartu Parish. Before the 2017 administrative reform, the island encompassed Piirissaare Parish, which, before its dissolution, was the smallest rural municipality by population in Estonia. As of the 2011 census, Piirissaar had 53 resident down from 104 in 2000.