Olszewo [ɔlˈʂɛvɔ] is a village in the administrative district of Gmina Mikołajki, within Mrągowo County, Warmian-Masurian Voivodeship, in northern Poland. It lies approximately 10 kilometres (6 mi) north-east of Mikołajki, 25 km (16 mi) east of Mrągowo, and 78 km (48 mi) east of the regional capital Olsztyn.