In 2003, the International Society of Nephrology and the Working Group of the Renal Pathology Society (ISN/RPS) pathological staging was divided into six types. Type I is a mildly lesional LN: the light microscopic appearance is basically normal, and immunocomplex deposition in the thylakoid region is visible by immunofluorescence. Type II is thylakoid proliferative LN: light microscopy shows thylakoid cell hyperplasia or increased thylakoid stroma with immune complex deposition in the thylakoid region, and immunofluorescence or electron microscopy shows a small amount of isolated subepithelial or subendothelial deposits. Type III is focal LN: less than 50% of all glomeruli are involved, and may present as active or inactive lesions, focal, segmental or globular lesions, and intra- or extra-capillary hyperplastic lesions. Type III(A) is an active lesion that presents as focal hyperplastic LN; Type III(A/C) is an active with chronic lesion that presents as focal hyperplastic sclerosing nephritis; Type III(C) is a chronic lesion that presents as focal sclerosing nephritis. Type IV is diffuse LN: the affected glomeruli account for more than 50% of all glomeruli, and typical cases often have diffuse subendothelial immune complex deposits with or without thylakoid lesions. According to the glomerular lesions, there are diffuse segmental LN (the glomeruli are segmental) and diffuse globular LN (the glomeruli are globular). Type IVS(A) is active segmental hyperplastic LN, Type IVG(A) is active globular hyperplastic LN, Type IVS(AC) is active with chronic segmental hyperplastic sclerosing LN, Type IVG(A/C) is active with chronic globular hyperplastic sclerosing LN, Type IVS(C) is chronic segmental sclerosing LN, and Type IVG(C) is chronic globular sclerosing LN. Type V is membranous LN: subepithelial immune complex deposits are visible on light microscopy with or without thylakoid lesions. Immunofluorescence or electron microscopy reveals spherical or segmental subepithelial continuous immune complex deposits, and type V is often coexistent with type III or IV. Type VI is a progressive sclerosing LN: more than 90% of glomeruli are spherically sclerotic.