San Isidro, officially the Municipality of San Isidro, is a 2nd class municipality in the province of Nueva Ecija, Philippines. According to the 2020 census, it has a population of 54,372 people. The municipality is bounded by Gapan to the east, the municipalities of San Leonardo and Jaen to the north, San Antonio to the west, Cabiao to the south-west, San Miguel, Bulacan, to the southeast and Candaba, Pampanga, to the south.