Sergach is a town located in Russia and serves as the administrative center of the Sergachsky District. It is situated on the Pyana River, approximately 150 kilometers (93 mi) southeast of Nizhny Novgorod, which is the administrative center of the oblast.
According to census data, the population of the town has fluctuated over recent decades. The 2010 census recorded a population of 21,386, following figures of 22,887 in 2002 and 25,231 during the 1989 Soviet census.