A case of visceral Leishmaniasis in a renal transplant recipient is reported because of its peculiar clinical presentation: the presence of most clinical signs of the disease, such as high-grade fever, marked leucopenia, and splenomegaly, but persistent negativity of serology and of bone marrow smear. Forty days after the first bone marrow biopsy, the diagnosis was made possible by a second biopsy, and the treatment was started with antimonial compounds, which led to complete remission of symptoms. A relapse was observed 1 month after discontinuation of therapy, successfully treated with a new cycle of the same drug and allopurinol. The diagnosis of Leishmaniasis must always be considered in immunosuppressed transplant recipients with fever and leucopenia of unknown origin, even when serology and bone marrow smear are negative.