Leishmaniasis is an infectious disease caused by protozoa of the Leishmania genus, parasites of humans and several domestic and wild animals, and transmitted via vectors. The authors describe the case of an 18-month-old girl, presenting to the Emergency Room for persistent fever, hepatosplenomegaly and regression of developmental milestones. Blood exams show trilineage cytopenia and increased hepatic cytolysis indexes. The patient underwent peripheral blood smear and bone marrow aspirate, all of which resulted normal, ruling out the primary suspicion of lymphoproliferative disease. The finding of anti-leishmania antibodies, the positivity of PCR investigation and the evidence of Leishmania protozoa on the bone marrow aspirate in optical microscopy confirmed the diagnosis of Visceral Leishmaniasis. The patient was therefore treated with Amphotericin B with rapid resolution of fever, reduction of cytolysis indexes and general clinical improvement.