A new species of Tacinga from semi-arid Eastern Brazil, Tacinga paiaia, is here described on the basis of material collected several years ago and cultivated at the Cactarium Guimarães Duque of the Instituto Nacional do Semiárido. A detailed description, original illustrations, distribution map, a taxonomic discussion for the new taxon, and a key to all known species of Tacinga are given. We also assessed the IUCN risk of extinction category for the new species. It is here preliminarily classified as Vulnerable to extinction due to its small population size and restricted distribution. Finally, we also report the presence of extrafloral nectaries in the pericarpel areoles of the new taxon.