Gręzów [ˈɡrɛ̃zuf] is a village in the administrative district of Gmina Kotuń, within Siedlce County, Masovian Voivodeship, in east-central Poland. It lies approximately 5 kilometres (3 mi) east of Kotuń, 10 km (6 mi) west of Siedlce, and 78 km (48 mi) east of Warsaw.