The patron saint of San Donà di Piave is Our Lady of the Rosary, celebrated on the Monday after the first Sunday of October. The most important event of the town's year is the traditional Fiera del Rosario, popularly called «Le Fiere»: it is held on the first Monday of October and during the week immediately preceding it, drawing tens of thousands of visitors. The fair's origins are not known with certainty, but it appears to date from before the 17th century; according to some accounts, it can be traced back to the Battle of Lepanto, whose victory was consecrated precisely to the Virgin of the Rosary.
Every year, on 7 August, the town also re-enacts the Gaudium Sancti Donati, a historical commemoration of the Solemn Pact of Friendship: a great celebration is organised in the town centre, with shows, music and traditional medieval-inspired costumes.
