Disorders of glomerular structure and function are encountered frequently in clinical medicine. Many arise as part of a well-defined multisystem or multi-organ disease process, while in others the clinical and laboratory manifestations are consequent to the sole or predominant involvement of glomeruli. The latter are known as the primary glomerulopathies. These disorders can evoke a variety of clinical syndromes, including acute glomerulonephritis, rapidly progressive glomerulo-nephritis, nephrotic syndrome, "symptomless" hematuria and/or proteinuria, and chronic glomerulonephritis. The identification of underlying morphology, through the application of renal biopsy techniques, can provide useful information for both prognosis and treatment. Pathogenic mechanisms involved in the primary glomerulopathies are varied, but immunologic perturbations underlie many disease entities. This article describes the clinical features, pathology, natural history, and treatment of the main categories of primary glomerulonephritis, with emphasis on recent developments and practical aspects of diagnosis and management.