Świętajno [ɕfjɛnˈtai̯nɔ] (German: Schwentainen, 1938-45 Altenkirchen) is a village in Olecko County, Warmian-Masurian Voivodeship, in northern Poland. It is the seat of the gmina (administrative district) called Gmina Świętajno. It lies approximately 13 kilometres (8 mi) west of Olecko and 122 km (76 mi) east of the regional capital Olsztyn.
Before 1945 the area was part of Germany (East Prussia). After World War II the region was placed under Polish administration and ethnically cleansed according to the post-war Potsdam Agreement. The native German populace was expelled and replaced with Poles.
The village has a population of 1,600.
Coordinates: 54°0′5″N 22°19′3″E / 54.00139°N 22.31750°E