A 15-year clinical follow-up is reported for a familial glomerulopathy characterized on light microscopy by the glomerular deposition of giant fibrillary deposits (Virchows Arch A Pathol Anat Histol 388:313-326, 1980). On electron microscopy, the deposits consist of randomly oriented fibrils (12 to 16 nm in width and 120 to 170 nm in length). These deposits show positive immunoreactivity for fibronectin. One hundred fifty-seven of 197 family members within five generations were investigated. The disease is characterized by the occurrence of albuminuria in the third to fourth decades of life and slow progression to end-stage renal disease over a period of 15 to 20 years with the occurrence of generalized distal tubular acidosis (renal tubular acidosis type IV), hypertension, and the nephrotic syndrome. The frequent occurrence of otherwise unexplained microalbuminuria in young individuals of generations IV and V could be indicative of incipient glomerular disease. In one affected male individual and in his unaffected sister, renal cell carcinoma was diagnosed, raising the possibility that this familial glomerulopathy might be associated with an increased risk to develop renal cell cancer by direct or indirect (associated genetic predisposition) mechanisms. The disease relapsed in one renal transplant, raising the possibility of the presence of a transferable factor that could be part of the deposited fibrillar material or, alternatively, interfere with the glomerular handling of the deposited material.