Objective: Survey of Leishmania infantum chagasi in domestic and wild mammals in urban area and a Biological Reserve in Natal, Rio Grande do Norte, Brazil.Methods: Domestic and wild mammals were captured in Brazilian northeast Atlantic Rainforest, Rio Grande do Norte state. Serological and parasitological studies were conducted; Leishmania isolates were positioned in phylogeny based on small subunit rDNA (SSU rDNA) and glycosomal-3-phosphate dehydrogenase (gGAPDH) gene sequences.Results: Blood samples were collected from 138 wild and domestic mammals, comprising 66 dogs, 52 cats and 20 marsupials. Antibodies were found in 27 dogs (40.91%), two cats (3.85%) and one Didelphis albiventris (5%). The cultures of popliteal lymph node aspirates were positive in nine dogs (13.64%) and from seven (10.61%) the parasite was isolated and cryopreserved. All isolates were positioned in phylogeny based on SSU rDNA and gGAPDH in the same branch with L. infantum chagasi. Conclusions:The proximity of the forest fragment with humans and their domestic animals provide interference in the health of wild animals. Measures to control the population of feral cats and environmental conservation should be implemented due the importance of visceral leishmaniasis.