The renal glomerulus and its components have been intensively studied using microscopy - both light and electron - for decades and much has been learnt about their role in the pathogenesis of chronic kidney diseases such as diabetic nephropathy. In order to get more than purely qualitative information from the images, stereological tools have been applied to obtain unbiased quantitative data and thus allow structural-functional relationships to be explored. These techniques are likely to continue to be used in the coming decades in order to provide vital information about the disease process, complementing knowledge obtained from molecular techniques.