A 37-year-old splenectomized man affected by beta-thalassemia and chronic hepatitis, recently treated with pegylated interferon-alpha (Peg-IFN), was admitted because of elevated fever lasting 3 months and unresponsiveness to broad-spectrum antibiotics. Laboratory studies showed white blood cell and platelet counts within the normal range but lower than observed before Peg-IFN treatment and an elevated erythrocyte sedimentation rate. The blood transfusion rate was reported to be increased compared with the period preceding Peg-IFN treatment. A diagnosis of visceral leishmaniasis (VL) was made after Leishmania amastigotes were identified from Giemsa-stained smears of bone marrow aspirates. Cure occurred after liposomal amphotericin B was administered. Symptoms of VL may be difficult to distinguish from the manifestations of Peg-IFN intolerance. We suggest that VL must be suspected in any immunodepressed patient with an unexplained fever and a history of exposure in an endemic area.