Pervomaysky District (Russian: Первома́йский райо́н) was an administrative and municipal district (raion) in Nizhny Novgorod Oblast, Russia. It was located in the south of the oblast. The area of the district was 1,227.3 square kilometers (473.9 sq mi). Its administrative center was the town of Pervomaysk. Population: 20,455 (2010 Census); 22,344 (2002 Census); 26,926 (1989 Census). The population of Pervomaysk accounted for 71.2% of the district's total population.