Bolonchen or Bolonchen de Rej n is a town in Campeche State, Mexico, about 120 km west from the city of Campeche. The name "Bolonchen" means "Nine Wells" in the Maya language. "de Rej n" commemorates Manuel Crescencio Rej n, a lawyer who helped draft Mexico's constitution who was born here. In 1995 the town had a population of 3,487 people.

A good sized ruined site of the Pre-Columbian Maya civilization is centered just north of the modern town. It dates to the classic and postclassic periods. Most of the carved stone on the ancient structures was removed in the 18th century through the mid 20th century for reuse in modern construction. None the less, a few monuments with scupture and heiroglyphic texts are still visible at old Bolonchen.

A short distance to the south of Bolonchen are the caves of Xtacunbilxunan.

Both the ruins and cave were visited and described briefly by John Lloyd Stephens at the start of the 1840s, but no detailed scholarly examination of the ruins was made until that of Eric von Euw in 1973 (in part because Stephens and other early visitors failed to note that there were surviving inscriptions).