Glomerular disorders in which the manifestations of disease are primarily confined to the kidneys, without multisystem involvement, are not only common but very heterogeneous in terms of pathogenesis and clinical features. Typically, these primary glomerular diseases are characterized according to the findings on renal biopsy, as studied by light, immunofluorescence, and electron microscopy. The principal primary glomerular diseases are minimal change disease, focal and segmental glomerulosclerosis, membranous nephropathy, C3 glomerulonephritis and dense deposit disease, IgA nephropathy, and renal-limited crescentic glomerulonephritis. These clinicopathologic entities are discussed according to epidemiology, clinical features, pathology, pathogenesis (and genetics if appropriate), prognosis, and treatment, emphasizing recent findings. Key words: C3 glomerulonephritis, dense deposit disease, focal and segmental glomerulosclerosis, glomerulonephritis, IgA nephropathy, membranous nephropathy, minimal change disease, renal biopsy, renal-limited crescentic glomerulonephritis