Dłużek [ˈdwuʐɛk] (German: Hartigswalde) is a village in the administrative district of Gmina Jedwabno, within Szczytno County, Warmian-Masurian Voivodeship, in northern Poland.

It lies approximately 4 kilometres (2 mi) north-west of Jedwabno, 21 km (13 mi) west of Szczytno, and 29 km (18 mi) south-east of the regional capital Olsztyn.