Historically all Pilosocereus found on the island of Hispaniola have been assigned to the name P. polygonus. Field studies by the authors in Haiti and the Dominican Republic have identified four distinct taxa: P. polygonus and three others which cannot be attributed to any published name. We describe them here for the first time, as P. brevispinus sp. nov., P. excelsus sp. nov. and P. samanensis sp. nov. We provide a distribution map and key for the identification of the Pilosocereus species of Hispaniola. A replacement neotype is proposed for the name Pilocereus schlumbergeri to retain its current status as a synonym of P. polygonus.