Patients and Methods This is a retrospective study of collagen IV-related nephropathies patients followed at Instituto da Criança - HCFMUSP from 1999 to 2010. All patients presented glomerular hematuria (erythrocyte dysmorphism and/or red blood cell cast in the urinary sediment) and proteinuria. In 16 of 19 cases the diagnosis was based on familial history and renal histology findings which showed negative immunofluorescence and the ultrastructural abnormalities of the glomerular basement membrane (GBM) showing TBMN (uniform or diffuse attenuation of the GBM without the typical lamellation and thickening that is seen in AS) or AS (defects in terms of alternating attenuation, splitting, lamellation, and thickening along the GBM). However, it is very difficult to discriminate between the initial stage of AS and TBMN. Three patients were not submitted to renal biopsy since the familial history and the renal histology of relatives were characteristics of the disease. Only adherent patients were included, which was based on presence in attendance and exams.