Bais City is a 2nd class city in the province of Negros Oriental, Philippines. According to the 2000 census, it had a population of 68,115 people in 13,199 households. Located 44.7 km from the provincial capital Dumaguete, it has a land area of 316.90 km².
Bais City is the largest producer of raw sugar in Negros Oriental. There are two sugar mills in the city. The Central Azucarera de Bais was established by Tabacalera of Spain in the early 1900s and is one of the oldest in the country. The other mill, URSUMCO (United Robina Sugar Milling Corporation) was formerly UPSUMCO (United Planters Milling Corporation) and constructed in the mid 70's by Marubeni Corporation of Japan as a project of Ignacio Montenegro (also of Spanish roots).
The Pelarta river runs beside the city center. There is, however, a dispute that the name Bais was taken after the eels locally called "Bais" that used to thrive in this river. The river has been the source of irrigation water for the nearby sugar farms. This has been vital in the success of sugar plantations in this area. This river also has a big influence on the city's geography, as it deposits sediments in the former mangrove areas during the (formerly annual) flood season. These former mangrove swamps have now dried out and become populated with residents. In the late seventies, under the government of Genaro Goni, there was established a river control system stretching from the city center towards the low lying areas in order to lessen flooding during the rainy season.