The diagnosis, prognosis, and heredity of glomerulonephritis, in 207 members of one family over five generations was determined. No evidence of significant renal insufficiency or renal associated mortality was found. A history of urinary tract infections was obtained from 58 percent of those with hematuria. Several of those with nephritis also had high-frequency hearing losses. Two females with histories of urinary infections had elevated levels of serum creatinine. Many cases will probably be discovered if families are tested when a patient presents with benign recurrent hematuria with or without red blood cell casts. There may not be an obvious history of kidney disease or hematuria. Hereditary nephritis is not always a progressive renal disease.