Leishmaniasis is a vector-borne disease caused by protozoan parasites of the genus Leishmania. It is transmitted by phlebotomine female sand flies of the genera Phlebotomus and Lutzomyia in the old and new world, respectively. More than 20 well-recognized Leishmania species are known to infect humans and cause visceral (VL), cutaneous (CL) and mucocutaneous (ML) forms of the disease. Approximately 350 million people are at risk of contracting the disease and an estimated 1.6 million new cases occur annually. The disease mainly affects poor people in Africa, Asia and Latin America, and is associated with malnutrition, population migration, poor residency conditions, frail immune system and lack of resources. Previously, diagnosis of leishmaniasis relied mainly on invasive techniques of detecting parasites in splenic and bone marrow aspirates. Nevertheless, serological tests using the recombinant kinesin antigen (rK39) and molecular methods (polymerase chain reaction) are considered the best options for diagnosis today, despite problems related to varying sensitivities and specificities and field adaptability. Therapy of leishmaniasis ranges from local treatment of cutaneous lesions to systemic often toxic, therapy for disseminated CL, ML and VL. Agents with efficacy against leishmaniasis include amphotericin B, pentavalent antimonial drugs, paromomycin and miltefosine. No single therapy of VL currently offers satisfactory efficacy along with safety. This article provides a brief and updated systematic review on the epidemiology, diagnosis and treatment of this neglected disease.