Morphometric analysis was used to evaluate mesangial components in MCD (minimal changes disease), GNMes (mesangial glomerulonephritis), FSG (focal segmental glomerulosclerosis). In GNMes the increase of matrix was found to be generally proportional to the amount of mesangial cells. There are clear statistically significant differences in the ratio of matrix volume to cell component volume and of matrix volume to the whole mesangial area in MCD and GNMes as compared with FSG. In the case of GNMes where morphometric results resemble those in FSG cautious prognosis is recommended as there is a possibility of FSG. This has been confirmed both by the course of the disease and the results of repeated biopsy.