Two brothers with nephrotic syndrome are reported. Their parents were first cousins. The nephrotic syndrome developed at the age of 14 and 15 years and was resistant to the treatment with corticosteroid. The elder patient fell into renal failure about 2-1/2 years after the development of nephrotic syndrome, and the younger has demonstrated a progressive decrease in renal function. The renal histopathology in one patient revealed findings typical of focal glomerular sclerosis. In light of the clinical similarities in these two patients, it is likely that they have a familial form of focal glomerular sclerosis.