In the Region of the Americas, the leishmaniases are a group of diseases caused by various species of Leishmania, which cause a set of clinical syndromes in infected humans that can involve the skin, mucosa, and visceral organs. The spectrum of clinical disease is varied and depends on the interaction of several factors related to the parasite, the vector, and the host. Cutaneous leishmaniasis is the form most frequently reported in the Region and nearly 90% of cases present single or multiple localized lesions. Other cutaneous clinical forms, such as disseminated and diffuse cutaneous leishmaniasis, are more difficult to treat and relapses are common. The mucosal form is serious because it can cause disfigurement and severe disability if not diagnosed and treated early on. Visceral leishmaniasis is the most severe form, as it can cause death in up to 90% of untreated people.