Marciniaki [mart͡ɕiˈɲaki] (German: Martenshöh) is a village in the administrative district of Gmina Ostróda, within Ostróda County, Warmian-Masurian Voivodeship, in northern Poland. It lies approximately 4 kilometres (2 mi) east of Ostróda and 34 km (21 mi) west of the regional capital Olsztyn.
The village has a population of 20.