Background: Epidemiological data related to leishmaniasis or Leishmania infection in horses are scarce. However, studies carried out in different regions in the world showed equids parasitized by Leishmania braziliensis, L. infantum and L. martiniquensis. Objectives: Identify the Leishmania species causing cutaneous leishmaniasis in a mare, living in Rio de Janeiro state (Brazil), and search the presence of Leishmania viruses in the isolated parasite. METHODS: Isoenzymes and PCR targeting ITSrDNA region followed by sequencing were conducted for typing the isolated parasite. A search for Leishmania virus infection was also performed. Findings: The mare presented skin nodules and ulcers in the left pinna caused by Leishmania spp. that was detected by culture and PCR. The parasite was identified as Leishmania (Mundinia) martiniquensis, infected by Leishbunyavirus (LBV), representing the first description of this species in South America. The animal travelled to different Brazilian regions, but not to outside the country. Main Conclusions: The worldwide distribution of L. martiniquensis and its infection by LBV were confirmed in this study, indicating the autochthonous transmission cycle in Brazil. The clinical profile of the disease in the mare, showing fast spontaneous healing of cutaneous lesions, may indicate that skin lesions related to L. martiniquensis infection in horses might be underdiagnosed.