The occurrence of renal amyloidosis and fibrillary glomerulonephritis in the same biopsy specimen is exceptional and poses a diagnostic challenge. We describe the case of a non-Hispanic White patient with end-stage kidney disease due to fibrillary glomerulonephritis who received a second living donor kidney from a Hispanic individual. A 40-month–posttransplantation biopsy performed for an elevated serum creatinine level revealed interstitial congophilic deposits and glomerular noncongophilic fibrillary deposits, in addition to rejection. Separate laser microdissections of the glomerular and interstitial deposits followed by liquid chromatography–tandem mass spectrometry (LC MS/MS) revealed DNAJB9 peptide spectra in glomeruli and a peptide profile consistent with leukocyte chemotactic factor 2 (ALECT2) amyloidosis in the interstitium. Based on these findings, a 2-week–posttransplantation biopsy was re-reviewed and analyzed using LC MS/MS, which revealed a peptide profile consistent with ALECT2 amyloidosis in the interstitium, without peptide spectra for ALECT2 or DNAJB9 in glomeruli. The findings were consistent with donor-derived ALECT2 amyloidosis and recurrent fibrillary glomerulonephritis. At 49 months posttransplantation, allograft function was stable with minimal proteinuria. Thus, LC MS/MS was crucial to establish the accurate diagnosis of these 2 nephropathies characterized by fibrillary deposits. The indolent posttransplantation course suggests that donated kidneys with focal interstitial ALECT2 deposits may be suitable for transplantation but the deposits persist for many years.