The article begins by describing a dog with characteristic symptoms of visceral leishmaniasis. A serum sample from this animal was positive by indirect immunofluorescence (IIF) performed in anti-Leishmania total IgG in 1999. Tissues from the same dog were also positive by polymerase chain reaction (PCR) in 2004, identifying Leishmania DNA in the cerebellum, liver, kidney, and intestine. This is the first report of a dog with autochthonous visceral leishmaniasis in the county of Bom Sucesso, Minas Gerais State, Brazil. The finding of this IIF-positive dog led to a canine visceral leishmaniasis epidemiological investigation in the county. The investigation was conducted from March 1999 to December 2005. IIF was positive for Leishmania in 22 (3%) of 734 examined dogs. Among the 22 IIF-positive dogs, six presented characteristic symptoms of canine visceral leishmaniasis. The results of this epidemiological investigation were sent to local and State public health authorities, requesting visceral leishmaniasis control and preventive measures to interrupt transmission of the disease and avoid the occurrence of human cases.