Rzetnia [ˈʐɛtɲa] (German: Mühlbach) is a village in the administrative district of Gmina Kępno, within Kępno County, Greater Poland Voivodeship, in west-central Poland. It lies approximately 9 kilometres (6 mi) north-west of Kępno and 136 km (85 mi) south-east of the regional capital Poznań.
The village has a population of 750.