The volume densities of the cortical interstitium (CI), glomeruli and proximal tubular epithelium have been investigated on a sample involving 18 patients suffering from Balkan endemic nephropathy (BEN), classified into three groups with regard to the clearance of 99mTc-DTPA. In comparison with the control group, the evolution of the disease is marked by a significant increase of the CI volume (p<0.001), as well as a significant reduction of glomerular (p<0.01) and tubular volume densities (p<0.001). The most intensive changes of CI and glomerular volumes are characteristic of the initial stage of the disease when glomerular filtration (GF) has shown no signs of deterioration yet. On the other hand, a significant reduction of the tubular epithelium volume density is characteristic of the advanced stages. The specified changes, particularly those taking place at the level of interstitium bear the key responsibility for the BEN progression. However, a number of links constituting the chain of BEN morphogenesis remained insufficiently clarified. This urges for a precise quantification of all histological changes taking place in different stages of the disease, starting from the earliest, in order to get a better insight into the order and dynamics of their occurrence.