In routine diagnosis for renal biopsy, glomerular diseases are encountered that, viewed by electron microscopy, reveal deposits with a fibrillary structure in the extracellular matrix of the glomeruli. Amyloidosis is the most common glomerulopathy that shows deposits with an ultrastructural fibrillary structure. However, other glomerulopathies have deposits with an ultrastructural fibrillary structure and which are negative for Congo-red stain, but positive for immunoglobulins. Fibrillary glomerulonephritis is a well-characterized disease, and clearly identified in approximately 0.5% to 1% of biopsies of native kidneys. These cases usually manifest themselves as severe renal insufficiencies with nephrotic-range proteinuria. No treatment regimes have been clearly established and the prognosis is poor. Herein, the clinical and histological characteristics are described for the first case of idiopathic fibrillary glomerulonephritis reported in Colombia.