Chronic myelogenous leukemia (CML), hepatitis C, and interferon alpha (IFNalpha) have all been associated with renal dysfunction. In this paper we present a patient with the diagnosis of nephrotic syndrome and a known history of hepatitis C who received IFNalpha therapy for newly diagnosed CML. The renal biopsy showed focal segmental glomerulosclerosis, which has only been previously reported in two cases of CML treated with IFNalpha. There have also been two cases of patients with hepatitis C associated with focal segmental glomerulosclerosis. Despite the underlying hepatitis C, this case represents renal abnormalities consistent with IFNalpha therapy for CML.