Objective: Background:Rare disease Membranous glomerulonephritis can occur secondarily from infectious diseases. There are no reports describing membranous glomerulonephritis caused by non-tuberculous mycobacterium infection. However, several cases with membranous glomerulonephritis due to Mycobacterium tuberculosis have been reported. Mycobacterium shimoidei is an uncommon pathogen, and less than 20 cases with this species have been reported. A therapeutic regimen for this infection has not been established yet. Case Report: An 83-year-old Japanese man presented with productive cough for 6 months. Computed tomography scan showed multiple cavities in the bilateral pulmonary felds. Acid-fast bacilli were evident in his sputum by Ziehl-Neelsen staining (Gafky 3). PCR amplifcations for Mycobacterium tuberculosis, Mycobacterium avium, and Mycobacterium intracellulare were all negative. Finally, Mycobacterium shimoidei was identifed by rpoB sequencing and 16S rRNA sequencing. Urine examination showed a sub-nephrotic range of proteinuria and histology of the kidney showed membranous glomerulonephritis. Antimycobacterial treatment with clarithromycin, rifampicin, and ethambutol dramatically improved not only the pulmonary disease, but also the proteinuria. Conclusions: To the best of our knowledge, the presented case is the frst report showing non-tuberculous mycobacteriuminduced secondary membranous glomerulonephritis. A combination with clarithromycin, ethambutol, and rifampicin might be efective for treatment of Mycobacterium shimoidei infection. © Am J Case Rep.