Of 179 consecutive patients with glomerulonephritis 27 (15 percent) had focal glomerulosclerosis (FGS). Two of these 27 patients with FGS were sisters whose mother died of renal failure at 27 years of age. The father of another of these 27 patients with FGS died from renal failure at a young age. The third family included four members who reached end-stage failure. The findings from these three families suggested that FGS may be a familial or hereditary disease.