Fibrillary glomerulopathy is a category of glomerular disease that is defined by the ultrastructural feature of organized deposits of extracellular, nonbranching, microfibrils. The best-known disease in this category is amyloidosis, but cryoglobulinemia, light chain deposition disease, systemic lupus erythematosus, immunotactoid glomerulopathy, and diabetic fibrillosis may have similar ultrastructural findings and comprise the differential diagnosis of the fibrillary glomerulopathies. Because they have disease-specific therapeutic and prognostic implications, differentiating among these entities is important for nephrologists and nephropathologists. To aid the physician, we will review the fibrillary glomerulopathies using an algorithm based on morphology, clinical features, and serologic assessment. We believe this approach will prove to be practical and useful to the practicing nephrologist.