Viral infections can be the causative agent in many glomerular diseases, and diagnostic criteria include clinical and laboratory data and tissue molecular analysis. Hepatitis B virus (HBV) is a well known cause of membranous glomerulonephritis (MGN), membranoproliferative GN (MPGN) and IgA nephropathy (IgAN), frequently in Asian populations. Hepatitis C virus (HCV), besides cryoglobulinemia-mediated glomerulonephritis (GN), is reported to cause other forms of GN. Human immunodeficiency virus (HIV) infection is closely related to a collapsing focal segmental glomerulosclerosis (FSGS), a distinct disease that affects mainly Africans and African-Americans. In the course of HIV infection other immune complex (IC) GN can occur, most frequently in whites. Nephrotic syndrome and progression to renal insufficiency are the main clinical manifestations. HIV-HCV co-infection is related to an IC glomerular disease, sometimes with immunotactoid deposits. Recent reports emphasize the role of parvovirus B19 (PV B19) for "idiopathic" collapsing FSGS and ICGN, and of Coxsackie B virus for IgAN. Renal biopsy is useful for defining virus-related glomerular lesions and a guide for prognostic and therapeutic evaluation.