Gaczyska [ɡaˈt͡ʂɨska] is a village in the administrative district of Gmina Baranowo, within Ostrołęka County, Masovian Voivodeship, in east-central Poland. It lies approximately 5 kilometres (3 mi) south-west of Baranowo, 25 km (16 mi) north-west of Ostrołęka, and 105 km (65 mi) north of Warsaw.