Oľdza (Hungarian: Olgya, pronounced [ˈolɟɒ]) is a village and municipality in the Dunajská Streda District in the Trnava Region of south-west Slovakia.

Until the end of World War I, it was part of Hungary and fell within the Somorja district of Pozsony County.

After the Austro-Hungarian army disintegrated in November 1918, Czechoslovak troops liberated the area.

After Soviet liberation in 1945, Czechoslovak administration returned and the village became officially part of Czechoslovakia in 1947.

Roman Catholicism is the majority religion of the village, its adherents numbering 94.19% of the total population.