Seventy-three members of a 100-member kindred with asymptomatic proteinuria, nephrotic syndrome, and progressive renal failure were studied. Of those studied, 11 members had progressed to end-stage renal disease and seven had significant proteinuria (greater than 1 g/24 hours) with normal renal function. The genetic mode of inheritance was autosomal dominant with variable penetrance and expressivity. Histopathologic changes were variable but included focal segmental glomerulosclerosis and diffuse glomerulosclerosis. Renal failure usually occurred in the fifth decade of life. The most consistent clinical finding was proteinuria without microscopic hematuria or other significant urinary sediment elements. This disease differed from Alport's hereditary nephritis and congenital nephrotic syndrome in age of onset, urinary findings, and associated conditions, that is, nerve deafness. The hereditary proteinuria and nephrotic syndrome described in this kindred represents another facet in the spectrum of hereditary renal disease.