Invasive species are among the leading causes of biodiversity loss on the planet, and some species that have become invasive were intentionally introduced for ornamental or commercial purposes. Azadirachta indica A.Juss. (Indian neem) is an exotic species that is widely cultivated in the northeastern region of Brazil, both in plantations and as an ornamental or shade tree, where it has reached reproductive phase in recent years. In order to assess its level of naturalization and the geographic range where this species has reproductive capacity, we observed A. indica specimens cultivated in Fortaleza (Ceará) since 2006 and performed field observations in several other localities in Ceará, Rio Grande do Norte, Paraíba and Piauí states. Currently, the species reproduces near the coast as well as in the semiarid interior of the Northeast, and is able to establish regenerating populations. Thus, the species is naturalized in Brazil with the potential to become invasive in the near future.