Hepatitis C virus (HCV)-infection leads to chronic liver disease, but also to extra-hepatic manifestations, including kidney disease. We provide an overview of HCV-related kidney diseases in non-transplanted and in kidney transplant patients, and their therapies. Membranoproliferative glomerulonephritis, associated with Type 2 cryoglobulinemia, is the predominant Type of HCV-related glomerulonephritis. Membranous glomerulonephritis and focal segmental glomerular sclerosis are less commonly described. HCV infection seems to be linked to Type 2 diabetes mellitus, and might alter the progression of diabetic-related nephropathy. Patients infected by HCV should be annually screened for markers of kidney disease and, similarly, patients with membranoproliferative or membranous glomerulonephritis should be screened for HCV infection. After transplantation, cryoglobulinemia is frequent and is associated with HCV markers. HCV-related kidney disease requires specific treatment. In non-kidney-transplant patients, treatment relies on either only anti-HCV therapy in cases of moderate renal disease, or combined anti-viral and immunosuppressive therapies in cases of severe renal disease, i.e., nephrotic syndrome and/or progressive renal failure, and in diseases that are refractory to anti-HCV therapy. In kidney transplant patients, ribavirin monotherapy could be used cautiously, whereas rituximab might be a treatment of choice in the presence of cryoglobulinemia. In liver-transplant patients, in addition to anti-HCV therapy, rituximab might be also used.