The usual clinical course of focal segmental glomerulosclerosis is marked by progressive decrease in renal functional and sclerosis on biopsy over a period of months to years. We report a variant exemplified by 2 children who developed chronic renal failure within 12 weeks of the onset of nephrotic syndrome; repeat renal biopsies demonstrated extensive extracapillary glomerular proliferation and crescent formation. Both were males, less than 5 years of age, presenting with nephrotic syndrome resistant to steroid therapy and normal renal function. Renal biopsies done after 8 weeks of therapy, demonstrated findings compatible with focal segmental glomerulosclerosis. Within 12 weeks of onset of nephrotic syndrome, both patients experienced a decrease in renal function requiring dialysis. Repeat renal biopsies revealed extensive extracapillary glomerular proliferation with crescent formation. These patients represent a variant of focal segmental glomerulosclerosis characterized by rapid progression to renal failure with extensive extracapillary glomerular proliferation and crescent formation.