Focal and segmental glomerulosclerosis accounted for 4.1% of all primary glomerulopathies. Typical signs of focal and segmental glomerulosclerosis were striking arteriolosclerosis on histological examination, the urinary syndrome of high proteinuria with mild haematuria and frequent nephrotic syndrome. The ten-year cumulative percentage of remissions was 30%. Patients with remission had at the time of biopsy a normal serum creatinine level and no or minimal regressive tubulointerstitial changes. The ten-year cumulative percentage of renal failure was 40%. Presence of nephrotic syndrome, extracapillary proliferation and advanced tubulointerstitial changes, tended to shorten a kidney survival. In one third of the patients the serum creatinine level rose by more than 50 mol/1/year.